

Network Working Group                                         F. Strauss
Internet-Draft                                           TU Braunschweig
Expires: August 15, 2000                               February 15, 2000


           SMIng - A new Structure of Management Information
                        draft-irtf-nmrg-sming-02

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on August 15, 2000.

Abstract

   This memo presents a language for management information
   specifications. It eliminates known problems present in the current
   SMIv2 as specified in [2], [3], and [4]. Language extensibility
   features and a more efficient and programmer-friendly notation are
   introduced. Conversions from SMIv2 to SMIng and vice versa are also
   considered by this document. 

Copyright Notice

   Copyright (C) The Internet Society (2000). All Rights Reserved.












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Table of Contents

   1.       Introduction . . . . . . . . . . . . . . . . . . . . . .   6
   1.1      Terminology  . . . . . . . . . . . . . . . . . . . . . .   6
   1.2      Relation to SNMP . . . . . . . . . . . . . . . . . . . .   6
   2.       The Information Model  . . . . . . . . . . . . . . . . .   8
   2.1      Identifiers  . . . . . . . . . . . . . . . . . . . . . .   9
   2.2      Object Identifier Hierarchy  . . . . . . . . . . . . . .  10
   2.3      Kinds of Nodes . . . . . . . . . . . . . . . . . . . . .  11
   2.4      Scalar and Columnar Objects' Instances . . . . . . . . .  12
   3.       Base Types and Derived Types . . . . . . . . . . . . . .  15
   3.1      OctetString  . . . . . . . . . . . . . . . . . . . . . .  15
   3.2      ObjectIdentifier . . . . . . . . . . . . . . . . . . . .  16
   3.3      Integer32  . . . . . . . . . . . . . . . . . . . . . . .  17
   3.4      Integer64  . . . . . . . . . . . . . . . . . . . . . . .  18
   3.5      Unsigned32 . . . . . . . . . . . . . . . . . . . . . . .  18
   3.6      Unsigned64 . . . . . . . . . . . . . . . . . . . . . . .  19
   3.7      Float32  . . . . . . . . . . . . . . . . . . . . . . . .  20
   3.8      Float64  . . . . . . . . . . . . . . . . . . . . . . . .  21
   3.9      Float128 . . . . . . . . . . . . . . . . . . . . . . . .  22
   3.10     Enumeration  . . . . . . . . . . . . . . . . . . . . . .  23
   3.11     Bits . . . . . . . . . . . . . . . . . . . . . . . . . .  23
   3.12     Display Formats  . . . . . . . . . . . . . . . . . . . .  24
   4.       The SMIng File Structure . . . . . . . . . . . . . . . .  27
   4.1      Comments . . . . . . . . . . . . . . . . . . . . . . . .  27
   4.2      Statements and Arguments . . . . . . . . . . . . . . . .  27
   5.       The module Statement . . . . . . . . . . . . . . . . . .  28
   5.1      The module's import Statement  . . . . . . . . . . . . .  28
   5.2      The module's organization Statement  . . . . . . . . . .  29
   5.3      The module's contact Statement . . . . . . . . . . . . .  29
   5.4      The module's description Statement . . . . . . . . . . .  29
   5.5      The module's reference Statement . . . . . . . . . . . .  29
   5.6      The module's revision Statement  . . . . . . . . . . . .  29
   5.6.1    The revision's date Statement  . . . . . . . . . . . . .  30
   5.6.2    The revision's description Statement . . . . . . . . . .  30
   5.7      The module's identity Statement  . . . . . . . . . . . .  30
   5.8      Usage Example  . . . . . . . . . . . . . . . . . . . . .  30
   6.       The extension Statement  . . . . . . . . . . . . . . . .  32
   6.1      The extension's status Statement . . . . . . . . . . . .  32
   6.2      The extension's description Statement  . . . . . . . . .  32
   6.3      The extension's reference Statement  . . . . . . . . . .  32
   6.4      The extension's abnf Statement . . . . . . . . . . . . .  33
   7.       The typedef Statement  . . . . . . . . . . . . . . . . .  34
   7.1      The typedef's type Statement . . . . . . . . . . . . . .  34
   7.2      The typedef's default Statement  . . . . . . . . . . . .  34
   7.3      The typedef's format Statement . . . . . . . . . . . . .  34
   7.4      The typedef's units Statement  . . . . . . . . . . . . .  35
   7.5      The typedef's status Statement . . . . . . . . . . . . .  35
   7.6      The typedef's description Statement  . . . . . . . . . .  36


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   7.7      The typedef's reference Statement  . . . . . . . . . . .  36
   7.8      Usage Examples . . . . . . . . . . . . . . . . . . . . .  36
   8.       The node Statement . . . . . . . . . . . . . . . . . . .  38
   8.1      The node's oid Statement . . . . . . . . . . . . . . . .  38
   8.2      The node's status Statement  . . . . . . . . . . . . . .  38
   8.3      The node's description Statement . . . . . . . . . . . .  38
   8.4      The node's reference Statement . . . . . . . . . . . . .  38
   8.5      Usage Examples . . . . . . . . . . . . . . . . . . . . .  39
   9.       The scalar Statement . . . . . . . . . . . . . . . . . .  40
   9.1      The scalar's oid Statement . . . . . . . . . . . . . . .  40
   9.2      The scalar's type Statement  . . . . . . . . . . . . . .  40
   9.3      The scalar's access Statement  . . . . . . . . . . . . .  40
   9.4      The scalar's default Statement . . . . . . . . . . . . .  40
   9.5      The scalar's format Statement  . . . . . . . . . . . . .  41
   9.6      The scalar's units Statement . . . . . . . . . . . . . .  41
   9.7      The scalar's status Statement  . . . . . . . . . . . . .  41
   9.8      The scalar's description Statement . . . . . . . . . . .  42
   9.9      The scalar's reference Statement . . . . . . . . . . . .  42
   9.10     Usage Examples . . . . . . . . . . . . . . . . . . . . .  42
   10.      The table Statement  . . . . . . . . . . . . . . . . . .  43
   10.1     The table's oid Statement  . . . . . . . . . . . . . . .  43
   10.2     The table's status Statement . . . . . . . . . . . . . .  43
   10.3     The table's description Statement  . . . . . . . . . . .  43
   10.4     The table's reference Statement  . . . . . . . . . . . .  43
   10.5     The table's row Statement  . . . . . . . . . . . . . . .  44
   10.5.1   The row's oid Statement  . . . . . . . . . . . . . . . .  44
   10.5.2   Table Indexing Statements  . . . . . . . . . . . . . . .  44
   10.5.2.1 The row's index Statement for Table Indexing . . . . . .  44
   10.5.2.2 The row's augments Statement for Table Indexing  . . . .  44
   10.5.2.3 The row's sparse Statement for Table Indexing  . . . . .  45
   10.5.2.4 The row's reorders Statement for Table Indexing  . . . .  45
   10.5.2.5 The row's expands Statement for Table Indexing . . . . .  46
   10.5.3   The row's create Statement . . . . . . . . . . . . . . .  46
   10.5.4   The row's status Statement . . . . . . . . . . . . . . .  46
   10.5.5   The row's description Statement  . . . . . . . . . . . .  46
   10.5.6   The row's reference Statement  . . . . . . . . . . . . .  47
   10.6     The table row's column Statement . . . . . . . . . . . .  47
   10.6.1   The column's oid Statement . . . . . . . . . . . . . . .  47
   10.6.2   The column's type Statement  . . . . . . . . . . . . . .  47
   10.6.3   The column's access Statement  . . . . . . . . . . . . .  47
   10.6.4   The column's default Statement . . . . . . . . . . . . .  48
   10.6.5   The column's format Statement  . . . . . . . . . . . . .  48
   10.6.6   The column's units Statement . . . . . . . . . . . . . .  48
   10.6.7   The column's status Statement  . . . . . . . . . . . . .  49
   10.6.8   The column's description Statement . . . . . . . . . . .  49
   10.6.9   The column's reference Statement . . . . . . . . . . . .  49
   10.7     Usage Example  . . . . . . . . . . . . . . . . . . . . .  49
   11.      The notification Statement . . . . . . . . . . . . . . .  52
   11.1     The notification's oid Statement . . . . . . . . . . . .  52


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   11.2     The notification's objects Statement . . . . . . . . . .  52
   11.3     The notification's status Statement  . . . . . . . . . .  52
   11.4     The notification's description Statement . . . . . . . .  53
   11.5     The notification's reference Statement . . . . . . . . .  53
   11.6     Usage Example  . . . . . . . . . . . . . . . . . . . . .  53
   12.      The group Statement  . . . . . . . . . . . . . . . . . .  54
   12.1     The group's oid Statement  . . . . . . . . . . . . . . .  54
   12.2     The group's members Statement  . . . . . . . . . . . . .  54
   12.3     The group's status Statement . . . . . . . . . . . . . .  54
   12.4     The group's description Statement  . . . . . . . . . . .  54
   12.5     The group's reference Statement  . . . . . . . . . . . .  55
   12.6     Usage Example  . . . . . . . . . . . . . . . . . . . . .  55
   13.      The compliance Statement . . . . . . . . . . . . . . . .  56
   13.1     The compliance's oid Statement . . . . . . . . . . . . .  56
   13.2     The compliance's status Statement  . . . . . . . . . . .  56
   13.3     The compliance's description Statement . . . . . . . . .  56
   13.4     The compliance's reference Statement . . . . . . . . . .  56
   13.5     The compliance's mandatory Statement . . . . . . . . . .  56
   13.6     The compliance's optional Statement  . . . . . . . . . .  57
   13.6.1   The optional's description Statement . . . . . . . . . .  57
   13.7     The compliance's refine Statement  . . . . . . . . . . .  57
   13.7.1   The refine's type Statement  . . . . . . . . . . . . . .  58
   13.7.2   The refine's writetype Statement . . . . . . . . . . . .  58
   13.7.3   The refine's access Statement  . . . . . . . . . . . . .  58
   13.7.4   The refine's description Statement . . . . . . . . . . .  58
   13.8     Usage Example  . . . . . . . . . . . . . . . . . . . . .  58
   14.      SMIng Core Modules . . . . . . . . . . . . . . . . . . .  60
   14.1     IRTF-NMRG-SMING  . . . . . . . . . . . . . . . . . . . .  60
   14.2     IRTF-NMRG-SMING-TYPES  . . . . . . . . . . . . . . . . .  61
   14.3     IRTF-NMRG-SMING-EXTENSIONS . . . . . . . . . . . . . . .  80
   15.      Extending a Module . . . . . . . . . . . . . . . . . . .  83
   16.      SMIng Language Extensibility . . . . . . . . . . . . . .  85
   17.      Module Conversions . . . . . . . . . . . . . . . . . . .  87
   17.1     Converting SMIv2 to SMIng  . . . . . . . . . . . . . . .  87
   17.2     Converting SMIng to SMIv2  . . . . . . . . . . . . . . .  87
   17.3     SMIv1  . . . . . . . . . . . . . . . . . . . . . . . . .  87
   18.      Security Considerations  . . . . . . . . . . . . . . . .  88
   19.      Acknowledgements . . . . . . . . . . . . . . . . . . . .  89
            References . . . . . . . . . . . . . . . . . . . . . . .  90
            Author's Address . . . . . . . . . . . . . . . . . . . .  91
   A.       The SMIng ABNF grammar . . . . . . . . . . . . . . . . .  92
   B.       Glossary . . . . . . . . . . . . . . . . . . . . . . . . 104









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1. Introduction

   Management information is viewed as a collection of managed objects,
   residing in a virtual information store, termed the Management
   Information Base (MIB).  Collections of related objects are defined
   in MIB modules.  These modules are written conforming to a
   specification language, the Structure of Management Information
   (SMI). There are different versions of the SMI. SMIv1 [5], [6], [7]
   and SMIv2 [2], [3], [4] are based on adapted subsets of OSI's
   Abstract Syntax Notation One, ASN.1 [9]. It is the purpose of this
   document to define a successor of SMIv1 and SMIv2, the SMIng, in a
   self-contained way independent from other standardization bodies'
   documents. 

   Section 2 gives an overview of some basic concepts of the
   information model while the subsequent sections present the concepts
   of SMIng: the base types, the SMIng file structure, and all SMIng
   statements in detail. Section 14 contains three core modules that
   are part of the SMIng specification.  Section 15 lists rules to
   follow when changes are applied to a module. One flexible feature of
   SMIng is its extensibility which is described in Section 16.
   Finally, Section 17 discusses conversions of SMIv2 modules to SMIng
   and vice versa.  Appendix A contains the grammar of SMIng in ABNF
   [8] notation. 

1.1 Terminology

   Many terms in SMIv1 and SMIv2 are derived from ASN.1. In some cases,
   SMIv1/v2 uses different terms for equal or similar language items
   without precise definitions. Appendix B presents a glossary of terms
   used throughout this document and in related SMIng documents. Also
   refer to the glossary and Appendix A to get detailed information on
   the syntax of single language items where not explained in place. 

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [1]. 

1.2 Relation to SNMP

   Although SMIng is primarily intended to be applied to the SNMP
   management framework [10], SMIng is designed to have as few
   relations to a specific management protocol as possible. However,
   there are some implications of SNMP on SMIv2 that have to be
   retained in SMIng: 

   o  In SNMP the last item on a list of objects used to identify a
      table row can be encoded without an explicit length encoding.
      This has to be expressed by the SMIng `implied' keyword. See


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      Section 10.5 for details. 

   o  SNMP allows to distinguish several related types "on the wire"
      while SMIng has a minimal but complete set of base types.  To
      keep SMIng compatible with the SNMP framework, additional types
      derived from SMIng base types are defined in the standard SMIng
      module IRTF-NMRG-SMING-TYPES (Section 14.2). 

   o  The encoding of values of type `Bits' in SNMP is dependent on
      their named number values. It is RECOMMENDED that they start at 0
      and be numbered contiguously to allow a compact encoding for use
      with SNMP. 

   o  SNMP implies some restrictions on indexing columnar objects:
      Those columns that are used for indexing have to be defined as
      non-accessible auxiliary objects, with two exceptions. Hence, the
      access level `noaccess' has to be retained in SMIng. 

   o  In order to achieve compatibility with SNMPv1 traps, the next to
      last sub-identifier of notification object identifiers SHOULD
      have the value zero. 






























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2. The Information Model

   Internet management is based on the model of "managed objects".  A
   managed object represents a class of any real or synthesized
   variable of systems that are to be managed. Those objects are
   organized hierarchically in an "object identifier tree", where only
   leaf nodes may represent objects. 

   Nodes may also identify tables, row definitions of tables,
   notifications, groups of objects and/or notifications, compliance
   statements, modules or other information.  Each node is identified
   by an unique "object identifier" value which is an ordered list of
   non-negative numbers, named "sub-identifiers", where the left-most
   sub-identifier refers to the node next to the root of the tree and
   the right-most sub-identifier refers to the node that is identified
   by the complete object identifier. 

   The SMI in general, and SMIng in particular, is the information
   model used to define and organize the structure of managed objects
   and related information. Thus, SMIng describes a language designed
   to specify management information in a way readable to computer
   programs, named MIB compilers, as well as to human readers. 

   Related management information is defined in MIB modules.  A module
   may refer to definitions from other modules by importing identifiers
   from those modules.  Each module may serve one or multiple purposes: 

   o  the definition of inter-related managed objects, notifications
      and groups of them, 

   o  the definition of (restricted) types for use in the local module
      or in other modules, 

   o  the definition of compliance statements for groups of objects and
      notifications to guide agent implementors in what they have to
      serve or implementors of management applications in what they can
      expect, 

   o  the definition of SMIng extensions to allow the local module or
      other modules to specify information beyond the scope of the base
      SMIng in a machine readable notation, 

   o  the definition of information beyond the scope of the base SMIng
      statements, based on locally defined or imported SMIng
      extensions, like capability statements for agent implementations. 

   This classification scheme does not imply a rigid taxonomy. For
   example, a "standard" module will normally include definitions of
   managed objects and a compliance statement. Similarly, an


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   "enterprise-specific" module might include definitions of managed
   objects and a capability statement based on an extension. Of course,
   a "standard" module may not contain capability statements. 

   Each module is identified by an upper-case identifier. The names of
   all standard modules must be unique (but different versions of the
   same module should have the same name).  Developers of enterprise
   modules are encouraged to choose names for their modules that will
   have a low probability of colliding with standard or other
   enterprise modules, e.g. by using the enterprise or organization
   name as a prefix. 

2.1 Identifiers

   Identifiers are used to identify different kinds of SMIng items by
   name. These names are valid in a namespace which is dependent on the
   SMIng item. Those items are 

   o  modules (Section 5), whose namespace is the global range of all
      SMIng definitions, 

   o  defined data types (Section 7), whose namespace is the local
      module where the type is defined, 

   o  elements of enumeration and bitset types (Section 3.10, Section
      3.11), whose namespace is the related type definition construct
      and all constructs using that type, 

   o  object identifier tree nodes of different kinds (Section 5, and
      Section 8 through Section 13), whose namespace is the local
      module where the node is defined, and 

   o  SMIng extension statements (Section 6), whose namespace is the
      local module where the extension is defined. 

   Each identifier starts with an upper-case or lower-case character,
   dependent on the kind of SMIng item, followed by zero or more
   letters, digits, and hyphens. 

   For all identifiers of a single kind of item defined in a namespace,
   the identifier MUST be unique and SHOULD NOT only differ in case. 
   Identifiers MUST NOT exceed 64 characters in length. Furthermore,
   the set of all identifiers defined in all modules of a single
   standardization body or organization SHOULD be unique and mnemonic.
   This promotes a common language for humans to use when discussing a
   module. 

   To reference an item that is defined in the local module, its
   definition MUST sequentially precede the reference. Thus, there MUST


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   NOT be any forward references, except in two cases: 

   1.  The optional module's `identity' statement, which is located
       near the head of a module, specifies an identity node, which is
       defined in a subsequent section of the local module. 

   2.  The specification of table indexing objects in a table row may
       include objects that cannot be defined without the definition of
       the current table row. Hence table indexing statements are
       allowed to include forward references. 

   To reference an item, that is defined in an external module it MUST
   be imported into the local module's namespace (Section 5.1).
   Identifiers that are neither defined nor imported MUST NOT be
   visible in the local module. On the other hand, all items defined in
   a module are implicitly exported. 

   Note when identifiers from external modules are referenced, there is
   the possibility of name collisions. As such, if different items with
   the same identifier are imported or if imported identifiers collide
   with identifiers of locally defined items, then this ambiguity is
   resolved by prefixing those identifiers with the names of their
   modules and the namespace operator `::', i.e. `Module::item'. Of
   course, this notation can be used to refer to identifiers even when
   there is no name collision. 

   Note that SMIng language keywords MUST NOT be imported. The main set
   of keywords are SMIng statements and base types. See the
   `...Keyword' rules of the SMIng ABNF grammar in Appendix A for a
   list of those keywords. 

   Finally, by convention, if the identifier refers to an object with a
   counter type (Counter32 or Counter64, derived from Unsigned32 and
   Unsigned64) then the identifier used for the object SHOULD denote
   plurality. 

2.2 Object Identifier Hierarchy

   The layers of the object identifier tree near the root are well
   defined and organized by standardization bodies. The first level
   next to the root has three nodes: 

      0: ccitt

      1: iso

      2: joint-iso-ccitt

   Note that the renaming of the Commite Consultatif International de


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   Telegraphique et Telephonique (CCITT) to International
   Telecommunications Union (ITU) had no consequence on the names used
   in the object identifier tree. 

   The root of the subtree administered by the Internet Assigned
   Numbers Authority (IANA) for the Internet is `1.3.6.1' which is
   assigned with the identifier `internet'. That is, the Internet
   subtree of object identifiers starts with the prefix `1.3.6.1.'. 

   Several branches underneath this subtree are used for network
   management: 

   The `mgmt' (internet.2) subtree is used to identify "standard"
   information. 

   The `experimental' (internet.3) subtree is used to identify
   information being designed by working groups of the IETF or IRTF. If
   a module produced by a working group becomes a "standard" module
   then at the very beginning of its entry onto the Internet standards
   track, the information is moved under the mgmt subtree. 

   The `private' (internet.4) subtree is used to identify information
   defined unilaterally. The `enterprises' (private.1) subtree beneath
   private is used, among other things, to permit providers of
   networking subsystems to register models of their products. 

   These and some other nodes are defined in the SMIng standard module
   IRTF-NMRG-SMING (Section 14.1). 

2.3 Kinds of Nodes

   Each node in the object identifier tree may be of a single kind
   which may represent management information or not: 

   o  simple nodes, that do not represent management information, but
      may be used for grouping nodes in a subtree, 

   o  nodes representing the identity of a module to allow references
      to a module in other objects of type `ObjectIdentifier', 

   o  scalar objects, which have zero or one object instance and no
      child nodes. See Section 2.4 for scalar objects' instances, 

   o  tables, which represent the root node of a collection of
      information structured in table rows. A table node SHOULD have no
      more child nodes than the single row node of this table, 

   o  rows, which belong to a table (that is, the table's full object
      identifier is a prefix of the row's object identifier) and


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      represent a sequence of one or more columnar objects. Those
      columnar objects MUST be the only child nodes of a table row. A
      row's object identifier MUST be constructed by appending a `1'
      sub-identifier to the table's object identifier, 

   o  columnar objects, which belong to a row (that is, the row's full
      object identifier is a prefix of the columnar objects' object
      identifier) and have zero or more object instances and no child
      nodes. Each columnar object's object identifier MUST be
      constructed by appending a single sub-identifier to the row's
      object identifier.  See Section 2.4 for columnar objects'
      instances, 

   o  notifications, which represent information that is sent by agents
      within unsolicited transmissions. A notification's object
      identifier SHOULD not have any child node, 

   o  groups of objects and notifications, which may be used for
      compliance statements or other purposes, 

   o  compliance statements which define requirements for MIB module
      implementations, 

   o  other nodes, that may be used to identify arbitrary information. 

2.4 Scalar and Columnar Objects' Instances

   Instances of managed objects are identified by appending an
   instance-identifier to the object's object identifier. Scalar
   objects and columnar objects use different ways to construct the
   instance-identifier. 

   Scalar objects have zero or one object instance. If it exists, it is
   identified by appending a single `0' sub-identifier to the object
   identifier of the scalar object. 

   Within tables, different instances of the same columnar object are
   identified by appending a sequence of one or more sub-identifiers to
   the object identifier of the columnar object which consists of the
   values of object instances that unambiguously distinguish a table
   row. These indexing objects can be columnar objects of the same
   and/or another table, but MUST NOT be scalar objects.  Multiple
   applications of the same object in a single table indexing
   specification are strongly discouraged. 

   The base types (Section 3) of the indexing objects indicate how to
   form the instance-identifier: 

   o  integer-valued or enumeration-valued: a single sub-identifier


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      taking the integer value (this works only for non-negative
      integers and integers of a size of up to 32 bits), 

   o  string-valued, fixed-length strings (or variable-length with
      compact encoding): `n' sub-identifiers, where `n' is the length
      of the string (each octet of the string is encoded in a separate
      sub-identifier), 

   o  string-valued, variable-length strings or bits-valued: `n+1'
      sub-identifiers, where `n' is the length of the string or bits
      encoding (the first sub-identifier is `n' itself, following this,
      each octet of the string or bits is encoded in a separate
      sub-identifier), 

   o  object identifier-valued (with compact encoding): `n'
      sub-identifiers, where `n' is the number of sub-identifiers in
      the value (each sub-identifier of the value is copied into a
      separate sub-identifier), 

   o  object identifier-valued: `n+1' sub-identifiers, where `n' is the
      number of sub-identifiers in the value (the first sub-identifier
      is `n' itself, following this, each sub-identifier in the value
      is copied), 

   Note that compact encoding can only be applied to an object having a
   variable-length syntax (e.g., variable-length strings, bits objects
   or object identifier-valued objects). Further, compact encoding can
   only be associated with the last object in a list of indexing
   objects. Finally, compact encoding MUST NOT be used on a
   variable-length string object if that string might have a value of
   zero-length. 

   Instances identified by use of integer-valued or enumeration-valued
   objects are RECOMMENDED to be numbered starting from one (i.e., not
   from zero). Integer objects that allow negative values, Unsigned64
   objects, Integer64 objects and floating point objects MUST NOT be
   used for table indexing. 

   Objects which are both specified for indexing in a row and also
   columnar objects of the same row are termed auxiliary objects.
   Auxiliary objects SHOULD be non-accessible, except in the following
   circumstances: 

   o  within a MIB module originally written to conform to SMIv1, or 

   o  a row must contain at least one columnar object which is not an
      auxiliary object.  In the event that all of a row's columnar
      objects are also specified to be indexing objects then one of
      them MUST be accessible. (Note that this situation does not arise


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      for a row allowing create access, since such a row will have a
      status column which will not be an auxiliary object.) 

















































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3. Base Types and Derived Types

   SMIng has a minimal but complete set of base types, similar to those
   of many programming languages, but with some differences due to
   special requirements from the management information model described
   in Section 2. 

   Additional types may be defined, derived from those base types and
   even from other derived types. Derived types may use subtyping to
   formally restrict the possible values. A set of derived types
   commonly used in the SNMP framework is defined in the SMIng standard
   module IRTF-NMRG-SMING-TYPES (Section 14.2). 

   Note that types can also be restricted "inline" in object
   definitions (Section 9, Section 10.6) or in refinements of
   compliance statements (Section 13) without referring an explicitly
   defined type. 

   The different base types and its derived types allow different kinds
   of subtyping, namely size restrictions and range restrictions. See
   the following sections on base types (Section 3.1 through Section
   3.11) for details. 

3.1 OctetString

   The OctetString base type represents arbitrary binary or textual
   data.  Although SMIng has a theoretical size limitation of 2^32-1
   (4294967295) octets for this base type, MIB designers should realize
   that there may be implementation and interoperability limitations
   for sizes in excess of 255 octets. 

   Values of octet strings may be denoted as textual data enclosed in
   double quotes or as arbitrary binary data denoted as a `0x'-prefixed
   hexadecimal value of arbitrary but even length, where each pair of
   hexadecimal digits represents a single octet. Letters in hexadecimal
   values MAY be upper-case but lower-case characters are RECOMMENDED.
   Textual data may contain any number (possibly zero) of any 7-bit
   displayable ASCII characters except double quote `"', including tab
   characters, spaces and line terminator characters (nl or cr & nl). 
   Textual data may span multiple lines, where each subsequent line
   prefix containing only white space up to the column where the first
   line's data starts SHOULD be skipped by parsers for a better text
   formatting. 

   When defining a type derived (directly or indirectly) from the
   OctetString base type, the size in octets may be restricted by
   appending a list of size ranges or explicit size values, separated
   by pipe `|' characters and the whole list enclosed in parenthesis. A
   size range consists of a lower bound, two consecutive dots `..' and


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   an upper bound. Each value can be given in decimal or `0x'-prefixed
   hexadecimal notation. Of course, size restricting values MUST NOT be
   negative. If multiple values or ranges are given, they all MUST be
   disjunct and SHOULD be in ascending order. If a size restriction is
   applied to an already size restricted octet string the new
   restriction MUST be more limiting, that is raising the lower bounds,
   reducing the upper bounds, reducing the alternative size choices, or
   splitting ranges into multiple ranges with intermediate gaps. 

   Value Examples: 

     "This is a multiline
      textual data example."         // legal
     "This is "illegally" quoted."   // illegal quotes
     "But this is 'ok'."             // legal apostrophe quoting
     ""                              // legal zero length
     0x123                           // illegal odd hex length
     0x534d496e670a                  // legal octet string

   Restriction Examples: 

     OctetString (0 | 4..255)        // legal size spec
     OctetString (4)                 // legal exact size
     OctetString (-1 | 1)            // illegal negative size
     OctetString (1 | 1..10)         // illegal overlapping

3.2 ObjectIdentifier

   The ObjectIdentifier base type represents any object identifier
   value, which is a list of up to 128 numbers, named sub-identifiers.
   Each sub-identifier has a value between 0 and 2^32-1 (4294967295). 

   Values of object identifiers may be denoted as a sequence of
   numerical sub-identifier values (decimal or `0x'-prefixed
   hexadecimal) separated by single dots and without any intermediate
   white space. Alternatively (and preferred in most cases), the first
   element may be a previously defined or imported lower-case
   identifier, representing a static object identifier prefix while the
   total number of sub-identifiers MUST NOT exceed 128 including the
   expanded identifier. 

   Object identifier derived types cannot be restricted in any way. 

   Value Examples: 







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     0                           // legal single subid
     1.3.6.1                     // legal numerical oid
     mib-2.1                     // legal oid with identifier prefix
     internet.4.1.0x0627.0x01    // legal oid with hex subids
     iso.-1                      // illegal negative subid
     iso.org.6                   // illegal non-heading identifier
     IF-MIB::ifNumber.0          // legel fully quallified instance oid

3.3 Integer32

   The Integer32 base type represents integer values between -2^31
   (-2147483648) and 2^31-1 (2147483647). 

   Values of type Integer32 may be denoted as decimal or hexadecimal
   numbers, where only decimal numbers can be negative. Other decimal
   numbers than zero MUST NOT have leading zero digits. Hexadecimal
   numbers are prefixed by `0x' and MUST have an even number of
   hexadecimal digits, where letters MAY be upper-case but lower-case
   characters are RECOMMENDED. 

   When defining a type derived (directly or indirectly) from the
   Integer32 base type, the set of possible values may be restricted by
   appending a list of ranges or explicit values, separated by pipe `|'
   characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. Each value can be given in decimal or `0x'-prefixed
   hexadecimal notation. If multiple values or ranges are given they
   all MUST be disjunct and SHOULD be in ascending order.  If a value
   restriction is applied to an already restricted type the new
   restriction MUST be more limiting, that is raising the lower bounds,
   reducing the upper bounds, reducing the alternative choices, or
   splitting ranges into multiple ranges with intermediate gaps. 

   Value Examples: 

     015                         // illegal leading zero
     -123                        // legal negative value
     - 1                         // illegal intermediate space
     0xabc                       // illegal hexadecimal value length
     -0xff                       // illegal sign on hex value
     0x80000000                  // illegal value, too large
     0xf00f                      // legal hexadecimal value

   Restriction Examples: 

     Integer32 (0 | 5..10)       // legal range spec
     Integer32 (4..8 | 5..10)    // illegal overlapping




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3.4 Integer64

   The Integer64 base type represents integer values between -2^63
   (-9223372036854775808) and 2^63-1 (9223372036854775807). 

   Values of type Integer64 may be denoted as decimal or hexadecimal
   numbers, where only decimal numbers can be negative. Other decimal
   numbers than zero MUST NOT have leading zero digits. Hexadecimal
   numbers are prefixed by `0x' and MUST have an even number of
   hexadecimal digits, where letters MAY be upper-case but lower-case
   characters are RECOMMENDED. 

   When defining a type derived (directly or indirectly) from the
   Integer64 base type, the set of possible values may be restricted by
   appending a list of ranges or explicit values, separated by pipe `|'
   characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. Each value can be given in decimal or `0x'-prefixed
   hexadecimal notation. If multiple values or ranges are given they
   all MUST be disjunct and SHOULD be in ascending order.  If a value
   restriction is applied to an already restricted type the new
   restriction MUST be more limiting, that is raising the lower bounds,
   reducing the upper bounds, reducing the alternative choices, or
   splitting ranges into multiple ranges with intermediate gaps. 

   Value Examples: 

     015                         // illegal leading zero
     -123                        // legal negative value
     - 1                         // illegal intermediate space
     0xabc                       // illegal hexadecimal value length
     -0xff                       // illegal sign on hex value
     0x80000000                  // legal value

   Restriction Examples: 

     Integer64 (0 | 5..10)       // legal range spec
     Integer64 (4..8 | 5..10)    // illegal overlapping

3.5 Unsigned32

   The Unsigned32 base type represents positive integer values between
   0 and 2^32-1 (4294967295). 

   Values of type Unsigned32 may be denoted as decimal or hexadecimal
   numbers. Other decimal numbers than zero MUST NOT have leading zero
   digits. Hexadecimal numbers are prefixed by `0x' and MUST have an
   even number of hexadecimal digits, where letters MAY be upper-case
   but lower-case characters are RECOMMENDED. 


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   When defining a type derived (directly or indirectly) from the
   Unsigned32 base type, the set of possible values may be restricted
   by appending a list of ranges or explicit values, separated by pipe
   `|' characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. Each value can be given in decimal or `0x'-prefixed
   hexadecimal notation. If multiple values or ranges are given they
   all MUST be disjunct and SHOULD be in ascending order.  If a value
   restriction is applied to an already restricted type the new
   restriction MUST be more limiting, that is raising the lower bounds,
   reducing the upper bounds, reducing the alternative choices, or
   splitting ranges into multiple ranges with intermediate gaps. 

   Value Examples: 

     015                         // illegal leading zero
     -123                        // illegal negative value
     0xabc                       // illegal hexadecimal value length
     0x80000000                  // legal hexadecimal value
     0x8080000000                // illegal value, too large]]>

   Restriction Examples: 

     Unsigned32 (0 | 5..10)       // legal range spec
     Unsigned32 (4..8 | 5..10)    // illegal overlapping

3.6 Unsigned64

   The Unsigned64 base type represents positive integer values between
   0 and 2^64-1 (18446744073709551615). 

   Values of type Unsigned64 may be denoted as decimal or hexadecimal
   numbers. Other decimal numbers than zero MUST NOT have leading zero
   digits. Hexadecimal numbers are prefixed by `0x' and MUST have an
   even number of hexadecimal digits, where letters MAY be upper-case
   but lower-case characters are RECOMMENDED. 

   When defining a type derived (directly or indirectly) from the
   Unsigned64 base type, the set of possible values may be restricted
   by appending a list of ranges or explicit values, separated by pipe
   `|' characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. Each value can be given in decimal or `0x'-prefixed
   hexadecimal notation. If multiple values or ranges are given they
   all MUST be disjunct and SHOULD be in ascending order.  If a value
   restriction is applied to an already restricted type the new
   restriction MUST be more limiting, that is raising the lower bounds,
   reducing the upper bounds, reducing the alternative choices, or
   splitting ranges into multiple ranges with intermediate gaps. 


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   Value Examples: 

     015                         // illegal leading zero
     -123                        // illegal negative value
     0xabc                       // illegal hexadecimal value length
     0x8080000000                // legal hexadecimal value

   Restriction Examples: 

     Unsigned64 (1..10000000000) // legal range spec

3.7 Float32

   The Float32 base type represents floating point values of single
   precision as described by [11]. 

   Values of type Float32 may be denoted as a decimal fraction with an
   optional exponent as known from many programming languages. See the
   grammar rule `floatValue' of Appendix A for the detailed syntax.
   Special values are `snan' (signaling Not-a-Number), `qnan' (quiet
   Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
   infinity).  Note that -0.0 and +0.0 are different floating point
   values.  0.0 is equal to +0.0. 

   When defining a type derived (directly or indirectly) from the
   Float32 base type, the set of possible values may be restricted by
   appending a list of ranges or explicit values, separated by pipe `|'
   characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. If multiple values or ranges are given they all MUST be
   disjunct and SHOULD be in ascending order.  If a value restriction
   is applied to an already restricted type the new restriction MUST be
   more limiting, that is raising the lower bounds, reducing the upper
   bounds, reducing the alternative choices, or splitting ranges into
   multiple ranges with intermediate gaps. The special values `snan',
   `qnan', `neginf', and `posinf' must be explicitly listed in
   restrictions if they shall be included, where `snan' and `qnan'
   cannot be used in ranges. 

   Note that encoding is not subject to this specification. It has to
   be described by protocols that transport objects of type Float32.
   Note also that most floating point encodings disallow the
   representation of many values that can be written as decimal
   fractions as used in SMIng for human readability. Therefore,
   explicit values in floating point type restrictions should be
   handled with care. 

   Value Examples: 



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     00.1                       // illegal leading zero
     3.1415                     // legal value
     -2.5E+3                    // legal negative exponential value

   Restriction Examples: 

     Float32 (-1.0..1.0)        // legal range spec
     Float32 (1 | 3.3 | 5)      // legal, probably unrepresentable 3.3
     Float32 (-10.0..10.0 | 0)  // illegal overlapping

3.8 Float64

   The Float64 base type represents floating point values of double
   precision as described by [11]. 

   Values of type Float64 may be denoted as a decimal fraction with an
   optional exponent as known from many programming languages. See the
   grammar rule `floatValue' of Appendix A for the detailed syntax.
   Special values are `snan' (signaling Not-a-Number), `qnan' (quiet
   Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
   infinity).  Note that -0.0 and +0.0 are different floating point
   values.  0.0 is equal to +0.0. 

   When defining a type derived (directly or indirectly) from the
   Float64 base type, the set of possible values may be restricted by
   appending a list of ranges or explicit values, separated by pipe `|'
   characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. If multiple values or ranges are given they all MUST be
   disjunct and SHOULD be in ascending order.  If a value restriction
   is applied to an already restricted type the new restriction MUST be
   more limiting, that is raising the lower bounds, reducing the upper
   bounds, reducing the alternative choices, or splitting ranges into
   multiple ranges with intermediate gaps. The special values `snan',
   `qnan', `neginf', and `posinf' must be explicitly listed in
   restrictions if they shall be included, where `snan' and `qnan'
   cannot be used in ranges. If 0.0 is included, -0.0 will also be. 

   Note that encoding is not subject to this specification. It has to
   be described by protocols that transport objects of type Float64.
   Note also that most floating point encodings disallow the
   representation of many values that can be written as decimal
   fractions as used in SMIng for human readability. Therefore,
   explicit values in floating point type restrictions should be
   handled with care. 

   Value Examples: 




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     00.1                       // illegal leading zero
     3.1415                     // legal value
     -2.5E+3                    // legal negative exponential value

   Restriction Examples: 

     Float64 (-1.0..1.0)        // legal range spec
     Float64 (1 | 3.3 | 5)      // legal, probably unrepresentable 3.3
     Float64 (-10.0..10.0 | 0)  // illegal overlapping

3.9 Float128

   The Float128 base type represents floating point values of quadruple
   precision as described by [11]. 

   Values of type Float128 may be denoted as a decimal fraction with an
   optional exponent as known from many programming languages. See the
   grammar rule `floatValue' of Appendix A for the detailed syntax.
   Special values are `snan' (signaling Not-a-Number), `qnan' (quiet
   Not-a-Number), `neginf' (negative infinity), and `posinf' (positive
   infinity).  Note that -0.0 and +0.0 are different floating point
   values.  0.0 is equal to +0.0. 

   When defining a type derived (directly or indirectly) from the
   Float128 base type, the set of possible values may be restricted by
   appending a list of ranges or explicit values, separated by pipe `|'
   characters and the whole list enclosed in parenthesis. A range
   consists of a lower bound, two consecutive dots `..' and an upper
   bound. If multiple values or ranges are given they all MUST be
   disjunct and SHOULD be in ascending order.  If a value restriction
   is applied to an already restricted type the new restriction MUST be
   more limiting, that is raising the lower bounds, reducing the upper
   bounds, reducing the alternative choices, or splitting ranges into
   multiple ranges with intermediate gaps. The special values `snan',
   `qnan', `neginf', and `posinf' must be explicitly listed in
   restrictions if they shall be included, where `snan' and `qnan'
   cannot be used in ranges. If 0.0 is included, -0.0 will also be. 

   Note that encoding is not subject to this specification. It has to
   be described by protocols that transport objects of type Float128.
   Note also that most floating point encodings disallow the
   representation of many values that can be written as decimal
   fractions as used in SMIng for human readability. Therefore,
   explicit values in floating point type restrictions should be
   handled with care. 

   Value Examples: 




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     00.1                       // illegal leading zero
     3.1415                     // legal value
     -2.5E+3                    // legal negative exponential value

   Restriction Examples: 

     Float128 (-1.0..1.0)       // legal range spec
     Float128 (1 | 3.3 | 5)     // legal, probably unrepresentable 3.3
     Float128 (-10.0..10.0 | 0) // illegal overlapping

3.10 Enumeration

   The Enumeration base type represents values from a set of integers
   in the range between -2^31 (-2147483648) and 2^31-1 (2147483647),
   where each value has an assigned name. The list of those named
   numbers has to be comma-separated, enclosed in parenthesis and
   appended to the `Enumeration' keyword. Each named number is denoted
   by its lower-case identifier followed by the assigned integer value,
   denoted as a decimal or `0x'-prefixed hexadecimal number, enclosed
   in parenthesis. Every name and every number in an enumeration type
   MUST be unique. It is RECOMMENDED that values start at 1 and be
   numbered contiguously. 

   Values of enumeration types may be denoted as decimal or
   `0x'-prefixed hexadecimal numbers or preferably as their assigned
   names. 

   When defining a type derived (directly or indirectly) from an
   enumeration type, the set of named numbers may be restricted by
   removing one or more named numbers.  But no named numbers may be
   added or changed regarding its name, value, or both. 

   Type and Value Examples: 

     Enumeration (up(1), down(2), testing(3))

     0                           // illegal, value 0 out of range
     up                          // legal value given by name
     2                           // legal value given by number

3.11 Bits

   The Bits base type represents bit sets. That is, a Bits value is a
   set of flags identified by small integer numbers starting at 0. 
   Each bit number has an assigned name. The list of those named
   numbers has to be comma-separated, enclosed in parenthesis and
   appended to the `Bits' keyword. Each named number is denoted by its
   lower-case identifier followed by the assigned integer value,
   denoted as a decimal or `0x'-prefixed hexadecimal number, enclosed


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   in parenthesis. Every name and every number in a bits type MUST be
   unique. It is RECOMMENDED that numbers start at 0 and be numbered
   contiguously. 

   Values of bits types may be denoted as a comma-separated list of
   decimal or `0x'-prefixed hexadecimal numbers or preferably their
   assigned names enclosed in parenthesis. There MUST NOT be any
   element (by name or number) listed more than once. It is RECOMMENDED
   to list elements in ascending order, although the order is
   semantically irrelevant. 

   When defining a type derived (directly or indirectly) from a bits
   type, the set of named numbers may be restricted by removing one or
   more named numbers.  But no named numbers may be added or changed
   regarding its name, value, or both. 

   Type and Value Examples: 

     Bits (readable(0), writeable(1), executable(2))

     ()                          // legal empty value
     (readable, writeable, 2)    // legal value
     (0, readable, executable)   // illegal, readable(0) appears twice
     (writeable, 4)              // illegal, element 4 out of range

3.12 Display Formats

   Some SMIng definitions, namely scalar and columnar object
   definitions and type definitions, allow the specification of a
   format to be used, when a value of that object or an object of that
   type is displayed. Format specifications are represented as textual
   data. 

   When the object or type has an underlying base type of Integer32,
   Integer64, Unsigned32, or Unsigned64, the format consists of an
   integer-format specification, containing two parts.  The first part
   is a single character suggesting a display format, either: `x' for
   hexadecimal, or `d' for decimal, or `o' for octal, or `b' for
   binary.  For all types, when rendering the value, leading zeros are
   omitted, and for negative values, a minus sign is rendered
   immediately before the digits.  The second part is always omitted
   for `x', `o' and `b', and need not be present for `d'.  If present,
   the second part starts with a hyphen and is followed by a decimal
   number, which defines the implied decimal point when rendering the
   value. For example `d-2' suggests that a value of 1234 be rendered
   as `12.34'. 

   When the object or type has an underlying base type of OctetString,
   the format consists of one or more octet-format specifications. 


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   Each specification consists of five parts, with each part using and
   removing zero or more of the next octets from the value and
   producing the next zero or more characters to be displayed.  The
   octets within the value are processed in order of significance, most
   significant first. 

   The five parts of a octet-format specification are: 

   1.  the (optional) repeat indicator; if present, this part is a `*',
       and indicates that the current octet of the value is to be used
       as the repeat count.  The repeat count is an unsigned integer
       (which may be zero) which specifies how many times the remainder
       of this octet-format specification should be successively
       applied.  If the repeat indicator is not present, the repeat
       count is one. 

   2.  the octet length: one or more decimal digits specifying the
       number of octets of the value to be used and formatted by this
       octet-specification.  Note that the octet length can be zero. 
       If less than this number of octets remain in the value, then the
       lesser number of octets are used. 

   3.  the display format, either: `x' for hexadecimal, `d' for
       decimal, `o' for octal, `a' for ASCII, or `t' for UTF-8 [12]. If
       the octet length part is greater than one, and the display
       format part refers to a numeric format, then network
       byte-ordering (big-endian encoding) is used interpreting the
       octets in the value.  The octets processed by the `t' display
       format do not necessarily form an integral number of UTF-8
       characters.  Trailing octets which do not form a valid UTF-8
       encoded character are discarded. 

   4.  the (optional) display separator character; if present, this
       part is a single character which is produced for display after
       each application of this octet-specification; however, this
       character is not produced for display if it would be immediately
       followed by the display of the repeat terminator character for
       this octet specification.  This character can be any character
       other than a decimal digit and a `*'. 

   5.  the (optional) repeat terminator character, which can be present
       only if the display separator character is present and this
       octet specification begins with a repeat indicator; if present,
       this part is a single character which is produced after all the
       zero or more repeated applications (as given by the repeat
       count) of this octet specification.  This character can be any
       character other than a decimal digit and a `*'. 

   Output of a display separator character or a repeat terminator


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   character is suppressed if it would occur as the last character of
   the display. 

   If the octets of the value are exhausted before all the octet format
   specification have been used, then the excess specifications are
   ignored.  If additional octets remain in the value after
   interpreting all the octet format specifications, then the last
   octet format specification is re-interpreted to process the
   additional octets, until no octets remain in the value. 

   Note that for some types (e.g. ObjectIdentifier) no format
   specifications are defined and SHOULD be omitted. Implementations
   MUST ignore format specifications they cannot interpret. Also note
   that the SMIng grammar (Appendix A) does not specify the syntax of
   format specifications. 

   Display Format Examples: 

     Base Type   Format              Example Value    Rendered Value
     ----------- ------------------- ---------------- -----------------
     OctetString 255a                "Hello World."   Hello World.
     OctetString 1x:                 "Hello!"         48:65:6c:6c:6f:21
     OctetString 1d:1d:1d.1d,1a1d:1d 0x0d1e0f002d0400 13:30:15.0,-4:0
     OctetString 1d.1d.1d.1d/2d      0x0a0000010400   10.0.0.1/1024
     OctetString *1x:/1x:            0x02aabbccddee   aa:bb/cc:dd:ee
     Integer32   d-2                 1234             12.34

























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4. The SMIng File Structure

   The topmost container of SMIng information is a file. An SMIng file
   may contain zero, one or more modules. It is RECOMMENDED to separate
   modules into files named by their modules, where possible. Though,
   for dedicated purposes it may be reasonable to collect several
   modules in a single file. 

   The top level SMIng construct is the `module' statement (Section 5)
   that defines a single MIB module.  A module contains a sequence of
   sections in an obligatory order with different kinds of definitions.
   Whether these sections contain statements or remain empty mainly
   depends on the purpose of the module (see Section 2). 

4.1 Comments

   Comments can be included at any position in an SMIng file, except in
   between the characters of a single token like those of a quoted
   strings.  However, it is RECOMMENDED that all substantive
   descriptions be placed within an appropriate description clause. 

   Comments commence with a pair of adjacent slashes `//' and end at
   the end of the line. 

4.2 Statements and Arguments

   SMIng has a very small set of basic grammar rules based on the
   concept of statements. Each statement starts with a lower-case
   keyword identifying the statement followed by a number (possibly
   zero) of arguments. An argument may be quoted text, an identifier, a
   value of any base type, a list of identifiers enclosed in
   parenthesis `( )' or a statement block enclosed in curly braces `{
   }'. Since statement blocks are valid arguments, it is possible to
   nest statement sequences. Each statement is terminated by a
   semicolon `;'. 

   The core set of statements may be extended using the SMIng
   `extension' statement. See Section 6 and Section 16 for details. 

   At places where a statement is expected, but an unknown lower-case
   word is read, those statements MUST be skipped up to the proper
   semicolon, including nested statement blocks. 









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5. The module Statement

   The `module' statement is used as a container of all definitions of
   a single SMIng MIB module. It gets two arguments: an upper-case
   module name and a statement block that contains mandatory and
   optional statements and sections of statements in an obligatory
   order: 

           module <MODULE-NAME> {

               <optional import statements>
               <organization statement>
               <contact statement>
               <description statement>
               <optional reference statement>
               <at least one revision statement>
               <optional identity statement>

               <optional extension statements>

               <optional typedef statements>

               <optional node/scalar/table statements>

               <optional notification statements>

               <optional group statements>

               <optional compliance statements>

           };

   The optional `import' statements are followed by the mandatory
   `organization', `contact', and `description' statements and the
   optional `reference' statement, which in turn are followed by the
   mandatory `revision' statements. This part defines the module's meta
   information while the following sections contain its main
   definitions. 

   See the `moduleStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `module' statement. 

5.1 The module's import Statement

   The optional module's `import' statement is used to import
   descriptors from external modules into the local module's namespace.
   It gets two arguments: the name of the external module and a
   comma-separated list of one or more identifiers to be imported
   enclosed in parenthesis. 


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   Multiple `import' statements for the same module but with disjunct
   lists of identifiers are allowed, though NOT RECOMMENDED. Anyhow,
   the same identifier from the same module MUST NOT be imported
   multiple times. To import identifiers with the same name from
   different modules might be necessary and is allowed. To distinguish
   them in the local module, they have to be referred by qualified
   names. It is NOT RECOMMENDED to import identifiers not used in the
   local module. 

   See the `importStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `import' statement. 

5.2 The module's organization Statement

   The module's `organization' statement, which must be present, gets
   one argument which is used to specify a textual description of the
   organization(s) under whose auspices this module was developed. 

5.3 The module's contact Statement

   The module's `contact' statement, which must be present, gets one
   argument which is used to specify the name, postal address,
   telephone number, and electronic mail address of the person to whom
   technical queries concerning this revision of this module should be
   sent. 

5.4 The module's description Statement

   The module's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the contents of this module. 

5.5 The module's reference Statement

   The module's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   management information, or some other document which provides
   additional information relevant to this module. 

5.6 The module's revision Statement

   The module's `revision' statement is repeatedly used to specify the
   editorial revisions of the module, including the initial revision.
   It gets one argument which is a statement block that holds detailed
   information in an obligatory order.  A module MUST have at least one
   initial `revision' statement. For every editorial change, a new one
   MUST be added in front of the revisions sequence, so that all
   revisions are in reverse chronological order. 


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   See the `revisionStatement' rule of the SMIng grammar (Appendix A)
   for the formal syntax of the `revision' statement. 

5.6.1 The revision's date Statement

   The revision's `date' statement, which must be present, gets one
   argument which is used to specify the date and time of the revision
   in the format `YYYY-MM-DD HH:MM' or `YYYY-MM-DD' which implies the
   time `00:00'. The time is always given in UTC. 

   See the `date' rule of the SMIng grammar (Appendix A) for the formal
   syntax of the revision's `date' statement. 

5.6.2 The revision's description Statement

   The revision's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the revision. 

5.7 The module's identity Statement

   The module's `identity' statement, which need not be present, gets
   one argument which specifies a node identifier within the local
   module, so that the object identifier of this node can be used to
   identify the module. 

5.8 Usage Example

   Consider how a skeletal MIB module might be constructed: e.g., 

   module FIZBIN-MIB {

     import IRTF-NMRG-SMING (experimental);

     organization
               "IETF SNMPv2 Working Group,
                IRTF Network Management Research Group (NMRG)";

     contact
               "        Frank Strauss

                Postal: TU Braunschweig
                        Bueltenweg 74/75
                        38106 Braunschweig
                        DE

                 Phone: +49 531 391-3266
                 EMail: strauss@ibr.cs.tu-bs.de";



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     description
               "The MIB module for entities implementing
                the xxxx protocol.";

     reference
               "RFC 2578, Section 5.7.";

     revision {
       date            "1999-09-28";
       description
               "Conversion from SMIv2 to SMIng.";
     };
     revision {
       date            "1995-05-24 18:11";
       description
               "Revision for RFC 1902.";
     };
     revision {
       date            "1992-10-07 04:33";
       description
               "The initial version of this MIB module,
                published in RFC 1442.";
     };

     identity fizbin;

     // ... further definitions ...

   }; // end of module FIZBIN-MIB.






















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6. The extension Statement

   The `extension' statement is used to define new statements to be
   used in the local module following this extension statement
   definition or in external modules that may import this extension
   statement definition. The `extension' statement gets two arguments:
   a lower-case extension statement identifier and a statement block
   that holds detailed extension information in an obligatory order. 

   Extension statement identifiers SHOULD NOT contain any upper-case
   characters or hyphens. 

   Note that the SMIng extension feature does not allow to formally
   specify the context, argument syntax and semantics of an extension.
   Its only purpose is to declare the existence of an extension and to
   allow a unique reference to an extension. See Section 16 for
   detailed information on extensions and Section 14.3 for a common
   example, the `agentcaps' extension. 

   See the `extensionStatement' rule of the SMIng grammar (Appendix A)
   for the formal syntax of the `extension' statement. 

6.1 The extension's status Statement

   The extension's `status' statement, which need not be present, gets
   one argument which is used to specify whether this extension
   definition is current or historic. The value `current' means that
   the definition is current and valid. The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated'
   also indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations. 

   If the `status' statement is omitted, the status value `current' is
   implied. 

6.2 The extension's description Statement

   The extension's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the extension statement. 

   It is RECOMMENDED to include information on the extension's context,
   its semantics, and implementation conditions. See also Section 16. 

6.3 The extension's reference Statement

   The extension's `reference' statement, which need not be present,


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   gets one argument which is used to specify a textual cross-reference
   to some other document, either another module which defines related
   extension definitions, or some other document which provides
   additional information relevant to this extension. 

6.4 The extension's abnf Statement

   The extension's `abnf' statement, which need not be present, gets
   one argument which is used to specify a formal ABNF [8] grammar
   definition of the extension. 

   Note that the `abnf' statement should contain only pure ABNF and no
   additional text, though comments prefixed by semicolon are allowed
   but should probably be moved to the description statement. Note also
   that double quotes are not allowed inside textual descriptions which
   are itself enclosed in double quotes. So they have to be replaced by
   single quotes. 


































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7. The typedef Statement

   The `typedef' statement is used to define new data types to be used
   in the local module or in external modules. It gets two arguments:
   an upper-case type identifier and a statement block that holds
   detailed type information in an obligatory order. 

   Type identifiers SHOULD NOT consist of all upper-case characters and
   SHOULD NOT contain hyphens. 

   See the `typedefStatement' rule of the SMIng grammar (Appendix A)
   for the formal syntax of the `typedef' statement. 

7.1 The typedef's type Statement

   The typedef's `type' statement, which must be present, gets one
   argument which is used to specify the type from which this type is
   derived. Optionally, type restrictions may be applied to the new
   type by appending subtyping information according to the rules of
   the base type.  See Section 3 for SMIng base types and their type
   restrictions. 

7.2 The typedef's default Statement

   The typedef's `default' statement, which need not be present, gets
   one argument which is used to specify an acceptable default value
   for objects of this type. A default value may be used at the
   discretion of an agent when an object instance is created. That is,
   the value is a "hint" to implementors. 

   The value of the `default' statement must, of course, correspond to
   the (probably restricted) type specified in the typedef's `type'
   statement. 

   The default value of a type may be overwritten by a default value of
   an object of this type. 

   Note that for some types, default values make no sense, e.g.
   IRTF-NMRG-SMING-TYPES::Counter32. 

7.3 The typedef's format Statement

   The typedef's `format' statement, which need not be present, gets
   one argument which is used to give a hint as to how the value of an
   instance of an object of this type might be displayed. See Section
   3.12 for a description of format specifications. 

   If no format is specified, it is inherited from the type given in
   the `type' statement.  On the other hand, the format specification


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   of a type may be overwritten by a format specification of an object
   of this type. 

7.4 The typedef's units Statement

   The typedef's `units' statement, which need not be present, gets one
   argument which is used to specify a textual definition of the units
   associated with objects of this type. 

   If no units are specified, they are inherited from the type given in
   the `type' statement.  On the other hand, the units specification of
   a type may be overwritten by a units specification of an object of
   this type. 

   The units specification has to be appropriate for values displayed
   according to the typedef's format specification, if present. E.g.,
   if the type defines frequency values of type Unsigned64 measured in
   thousands of Hertz, the format specification should be `d-3' and the
   units specification should be `Hertz' or `Hz'. If the format
   specification would be omitted, the units specification should be
   `Milli-Hertz' or `mHz'.  MIB Authors should pay attention to keep
   format and units specifications of type and object definitions
   synced. Application implementors MUST NOT implement units
   specifications without implementing format specifications. 

7.5 The typedef's status Statement

   The typedef's `status' statement, which need not be present, gets
   one argument which is used to specify whether this type definition
   is current or historic. The value `current' means that the
   definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated'
   also indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations. 

   Derived types SHOULD NOT be defined as `current' if their underlying
   type is `deprecated' or `obsolete'. Similarly, they SHOULD NOT be
   defined as `deprecated' if their underlying type is `obsolete'.
   Nevertheless, subsequent revisions of the underlying type cannot be
   avoided, but SHOULD be taken into account in subsequent revisions of
   the local module. 

   If the `status' statement is omitted, the status value `current' is
   implied. 





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7.6 The typedef's description Statement

   The typedef's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the newly defined type. 

   It is RECOMMENDED to include all semantic definitions necessary for
   implementation, and to embody any information which would otherwise
   be communicated in any commentary annotations associated with this
   type definition. 

7.7 The typedef's reference Statement

   The typedef's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   type definitions, or some other document which provides additional
   information relevant to this type definition. 

7.8 Usage Examples































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     typedef RptrOperStatus {
       type            Enumeration (other(1), ok(2), rptrFailure(3),
                                    groupFailure(4), portFailure(5),
                                    generalFailure(6));
       default         other;       // undefined by default.
       status          deprecated;
       description
               "A type to indicate the operational state
                of a repeater.";
       reference
               "[IEEE 802.3 Mgt], 30.4.1.1.5, aRepeaterHealthState.";
     };

     typedef DateAndTime {
       type            OctetString (8 | 11);
       format          "2d-1d-1d,1d:1d:1d.1d,1a1d:1d";
       status          current;     // could be omitted
       description
               "A date-time specification.
                ...
                Note that if only local time is known, then timezone
                information (fields 8-10) is not present.";
       reference
               "RFC 2579, SNMPv2-TC.DateAndTime.";
     };

     typedef Frequency {
       type            Unsigned64;
       format          "d-3"
       units           "Hertz";
       description
               "A wide-range frequency specification measured
                in thousands of Hertz.";
     };

















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8. The node Statement

   The `node' statement is used to name and describe a node in the
   object identifier tree, without associating object information with
   this node. This may be useful to group definitions in a subtree of
   related management information, or to uniquely define an identity of
   arbitrary kind to be referenced in objects of type ObjectIdentifier.
   The `node' statement gets two arguments: a lower-case node
   identifier and a statement block that holds detailed node
   information in an obligatory order. 

   See the `nodeStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `node' statement. 

8.1 The node's oid Statement

   The node's `oid' statement, which must be present, gets one argument
   which specifies the object identifier value that is assigned to this
   node. 

8.2 The node's status Statement

   The node's `status' statement, which need not be present, gets one
   argument which is used to specify whether this node definition is
   current or historic. The value `current' means that the definition
   is current and valid.  The value `obsolete' means the definition is
   obsolete and should not be implemented and/or can be removed if
   previously implemented.  While the value `deprecated' also indicates
   an obsolete definition, it permits new/continued implementation in
   order to foster interoperability with older/existing
   implementations. 

   If the `status' statement is omitted, the status value `current' is
   implied. 

8.3 The node's description Statement

   The node's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description
   of this node. 

   It is RECOMMENDED to include all semantics and purposes of this
   node. 

8.4 The node's reference Statement

   The node's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related


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   nodes, or some other document which provides additional information
   relevant to this node. 

8.5 Usage Examples

     node iso                            { oid 1;                };
     node   org                          { oid iso.3;            };
     node     dod                        { oid org.6;            };
     node       internet                 { oid dod.1;            };

     node   zeroDotZero {
         oid         0.0;
         description "A value used for null identifiers.";
         reference   "RFC 2578, 2. Definitions.";
     };




































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9. The scalar Statement

   The `scalar' statement is used to define a scalar managed object. 
   The `scalar' statement gets two arguments: a lower-case scalar
   identifier and a statement block that holds detailed object
   information in an obligatory order. 

   See the `scalarStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `scalar' statement. 

9.1 The scalar's oid Statement

   The scalar's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this scalar object. 

9.2 The scalar's type Statement

   The scalar's `type' statement, which must be present, gets one
   argument which is used to specify the data type of this scalar
   object. Optionally, type restrictions may be applied to the type by
   appending subtyping information according to the rules of the base
   type.  See Section 3 for SMIng base types and their type
   restrictions. 

9.3 The scalar's access Statement

   The scalar's `access' statement, which must be present, gets one
   argument which is used to specify whether it makes sense to read
   and/or write an instance of the object, or to include its value in a
   notification.  This is the maximal level of access for the object.
   This maximal level of access is independent of any administrative
   authorization policy. 

   The value `readwrite' indicates that read and write access makes
   sense. The value `readonly' indicates that read access makes sense,
   but write access is never possible. The value `notifyonly' indicates
   an object which is accessible only via a notification. 

   These values are ordered, from least to greatest access level:
   `notifyonly', `readonly', `readwrite'. 

9.4 The scalar's default Statement

   The scalar's `default' statement, which need not be present, gets
   one argument which is used to specify an acceptable default value
   for this scalar object. A default value may be used at the
   discretion of an agent when an object instance is created. That is,
   the value is a "hint" to implementors. 


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   The value of the `default' statement must, of course, correspond to
   the (probably restricted) type specified in the scalar's `type'
   statement. 

   The scalar's default value overrides the default value of the
   underlying type definition, if both are present. 

   Note that for objects of some types, default values make no sense,
   e.g. IRTF-NMRG-SMING-TYPES::Counter32. 

9.5 The scalar's format Statement

   The scalar's `format' statement, which need not be present, gets one
   argument which is used to give a hint as to how the value of an
   instance of this object might be displayed. See Section 3.12 for a
   description of format specifications. 

   The scalar's format specification overrides the format specification
   of the underlying type definition if both are present. 

9.6 The scalar's units Statement

   The scalar's `units' statement, which need not be present, gets one
   argument which is used to specify a textual definition of the units
   associated with this scalar object. 

   The scalar's units specification overrides the units specification
   of the underlying type definition if both are present. 

   The units specification has to be appropriate for values displayed
   according to the scalar's format specification if present. E.g., if
   the scalar object represents a frequency value of type Unsigned64
   measured in thousands of Hertz, the format specification should be
   `d-3' and the units specification should be `Hertz' or `Hz'. If the
   format specification would be omitted, the units specification
   should be `Milli-Hertz' or `mHz'.  MIB Authors should pay attention
   to keep format and units specifications of type and object
   definitions synced. Application implementors MUST NOT implement
   units specifications without implementing format specifications. 

9.7 The scalar's status Statement

   The scalar's `status' statement, which need not be present, gets one
   argument which is used to specify whether this scalar object
   definition is current or historic. The value `current' means that
   the definition is current and valid. The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated'
   also indicates an obsolete definition, it permits new/continued


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   implementation in order to foster interoperability with
   older/existing implementations. 

   Scalar objects SHOULD NOT be defined as `current' if their type is
   `deprecated' or `obsolete'. Similarly, they SHOULD NOT be defined as
   `deprecated' if their type is `obsolete'. Nevertheless, subsequent
   revisions of used type definition cannot be avoided, but SHOULD be
   taken into account in subsequent revisions of the local module. 

   If the `status' statement is omitted the status value `current' is
   implied. 

9.8 The scalar's description Statement

   The scalar's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of this scalar object. 

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this scalar object. 

9.9 The scalar's reference Statement

   The scalar's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   scalar objects, or some other document which provides additional
   information relevant to this scalar object. 

9.10 Usage Examples

     scalar dialCtlTrapEnable {
       oid             dialCtlConfiguration.2;
       type            Enumeration (enabled(1), disabled(2));
       access          readwrite;
       default         disabled;
       description
               "This object indicates whether dialCtlPeerCallInformation
                and dialCtlPeerCallSetup traps should be generated for
                all peers. If the value of this object is enabled(1),
                traps will be generated for all peers. If the value
                of this object is disabled(2), traps will be generated
                only for peers having dialCtlPeerCfgTrapEnable set
                to enabled(1).";
     };






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10. The table Statement

   The `table' statement is used to define the root node of a table. 
   The `table' statement gets two arguments: a lower-case table
   identifier and a statement block that holds detailed table
   information in an obligatory order. 

   See the `tableStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `table' statement. 

10.1 The table's oid Statement

   The table's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this table node. 

10.2 The table's status Statement

   The table's `status' statement, which need not be present, gets one
   argument which is used to specify whether this table definition is
   current or historic. The value `current' means that the definition
   is current and valid. The value `obsolete' means the definition is
   obsolete and should not be implemented and/or can be removed if
   previously implemented.  While the value `deprecated' also indicates
   an obsolete definition, it permits new/continued implementation in
   order to foster interoperability with older/existing
   implementations. 

   If the `status' statement is omitted the status value `current' is
   implied. 

10.3 The table's description Statement

   The table's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description
   of this table. 

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this table. 

10.4 The table's reference Statement

   The table's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   tables, or some other document which provides additional information
   relevant to this table. 




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10.5 The table's row Statement

   The table's `row' statement, which must be present, gets two
   arguments: a lower-case row identifier and a statement block that
   holds detailed row information in an obligatory order. 

   See the `rowStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `row' statement. 

10.5.1 The row's oid Statement

   The row's `oid' statement, which must be present, gets one argument
   which specifies the object identifier value that is assigned to this
   table row. Note that the object identifier of a table row MUST be
   built be the table's object identifier followed by a `1'
   sub-identifier. 

10.5.2 Table Indexing Statements

   SMIng offers five methods to supply table indexing information:
   ordinary tables, table augmentations, sparse table augmentations,
   table expansions, and reordered tables use different statements to
   denote their indexing information. Each table row definition must
   contain exactly one of the following indexing statements. 

10.5.2.1 The row's index Statement for Table Indexing

   The row's `index' statement, which is used to supply table indexing
   information of base table rows, gets at least one argument that
   specifies a comma-separated list of object identifiers, that are
   used for table indexing, enclosed in parenthesis. 

   Under some circumstances, an optional `implied' keyword may be added
   in front of the list to indicate a compact encoding of the last
   object in the list. See Section 2.4 for details. 

10.5.2.2 The row's augments Statement for Table Indexing

   The row's `augments' statement, which is used to supply table
   indexing information of table rows that augment a base table row,
   gets one argument that specifies the identifier of the table row to
   be augmented. Note that a row augmentation cannot itself be
   augmented. Anyhow, a base row may be augmented by multiple row
   augmentations. 

   A row augmentation makes instances of subordinate columnar objects
   identified according to the index specification of the base row
   corresponding to the row named in the `augments' statement. 
   Further, instances of subordinate columnar objects of a row


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   augmentation exist according to the same semantics as instances of
   subordinate columnar objects of the base row being augmented.  As
   such, note that creation of a base row implies the correspondent
   creation of any row augmentations. Row augmentations MUST NOT be
   used in row creation and deletion operations. 

10.5.2.3 The row's sparse Statement for Table Indexing

   The row's `sparse' statement, which is used to supply table indexing
   information of table rows that sparsely augment a base table row,
   gets one argument that specifies the identifier of the table row to
   be sparsely augmented. Note that a sparse row augmentation cannot
   itself be augmented. Anyhow, a base row may be augmented by multiple
   row augmentations, sparsely or not. 

   A sparse row augmentation makes instances of subordinate columnar
   objects identified, if present, according to the index specification
   of the base row corresponding to the row named in the `sparse'
   statement.  Further, instances of subordinate columnar objects of a
   sparse row augmentation exist according to the semantics as
   instances of subordinate columnar objects of the base row and the
   (non-formal) rules that confine the sparse relationship. As such,
   note that creation of a sparse row augmentation may be implied by
   the creation of a base row as well as done by an explicit creation.
   However, if a base row gets deleted, any dependent sparse row
   augmentations get also deleted implicitly. 

10.5.2.4 The row's reorders Statement for Table Indexing

   The row's `reorders' statement is used to supply table indexing
   information of table rows, that contain exactly the same index
   objects of a base table row, except in another order. It gets at
   least two arguments. The first one specifies the identifier of the
   base table row. The second one specifies a comma-separated list of
   exactly those object identifiers of the base row's `index'
   statement, but in the order to be used in this table. Note that a
   reordered table cannot itself be reordered. Anyhow, a base row may
   be used for multiple reordered tables. 

   Under some circumstances, an optional `implied' keyword may be added
   in front of the list to indicate a compact encoding of the last
   object in the list. See Section 2.4 for details. 

   Instances of subordinate columnar objects of a reordered table exist
   according to the same semantics as instances of subordinate columnar
   objects of the base row.  As such, note that creation of a base row
   implies the correspondent creation of any related reordered table.
   Rows or reordered tables MUST NOT be used in row creation and
   deletion operations. 


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10.5.2.5 The row's expands Statement for Table Indexing

   The row's `expands' statement is used to supply table indexing
   information of table row expansions. Table row expansions use
   exactly the same index objects of another row together with
   additional indexing objects. Thus, the `expands' statement gets at
   least two arguments. The first one specifies the identifier of the
   related table row. The second one specifies a comma-separated list
   of the additional object identifiers used for indexing. Note that an
   expanded table may itself be expanded, and related rows may be used
   for multiple table expansions. 

   Under some circumstances, an optional `implied' keyword may be added
   in front of the list to indicate a compact encoding of the last
   object in the list. See Section 2.4 for details. 

10.5.3 The row's create Statement

   The row's `create' statement, which need not be present, gets no
   argument. If the `create' statement is present, row creation (and
   deletion) is possible. 

10.5.4 The row's status Statement

   The row's `status' statement, which need not be present, gets one
   argument which is used to specify whether this row definition is
   current or historic. The value `current' means that the definition
   is current and valid. The value `obsolete' means the definition is
   obsolete and should not be implemented and/or can be removed if
   previously implemented.  While the value `deprecated' also indicates
   an obsolete definition, it permits new/continued implementation in
   order to foster interoperability with older/existing
   implementations. 

   If the `status' statement is omitted the status value `current' is
   implied. 

10.5.5 The row's description Statement

   The row's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description
   of this table row. 

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this table row. Especially, if the row's
   indexing statement contains objects that are not columnar objects of
   the row, it SHOULD be described how these objects are used in
   uniquely identifying instances of the row's columnar objects. 



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10.5.6 The row's reference Statement

   The row's `reference' statement, which need not be present, gets one
   argument which is used to specify a textual cross-reference to some
   other document, either another module which defines related table
   rows, or some other document which provides additional information
   relevant to this table row. 

10.6 The table row's column Statement

   The row's `column' statement is used to define a columnar managed
   object.  The `column' statement gets two arguments: a lower-case
   column identifier and a statement block that holds detailed object
   information in an obligatory order. 

   See the `columnStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `column' statement. 

10.6.1 The column's oid Statement

   The column's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this columnar object. 

10.6.2 The column's type Statement

   The column's `type' statement, which must be present, gets at least
   one argument which is used to specify the data type of this columnar
   object. Optionally, type restrictions may be applied to the type by
   appending subtyping information according to the rules of the base
   type.  See Section 3 for SMIng base types and their type
   restrictions. 

10.6.3 The column's access Statement

   The column's `access' statement, which must be present, gets one
   argument which is used to specify whether it makes sense to read
   and/or write an instance of the object, or to include its value in a
   notification.  This is the maximal level of access for the object.
   This maximal level of access is independent of any administrative
   authorization policy. 

   The value `readwrite' indicates that read and write access makes
   sense. The value `readonly' indicates that read access makes sense,
   but write access is never possible. The value `noaccess' indicates
   an auxiliary object (see Section 2.4).  The value `notifyonly'
   indicates an object which is accessible only via a notification. 

   These values are ordered, from least to greatest access level:


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   `noaccess', `notifyonly', `readonly', `readwrite'. 

10.6.4 The column's default Statement

   The column's `default' statement, which need not be present, gets
   one argument which is used to specify an acceptable default value
   for this columnar object. A default value may be used at the
   discretion of an agent when an object instance is created. That is,
   the value is a "hint" to implementors. 

   The value of the `default' statement must, of course, correspond to
   the (probably restricted) type specified in the column's `type'
   statement. 

   The column's default value overrides the default value of the
   underlying type definition if both are present. 

   Note that for objects of some types, default values make no sense,
   e.g. IRTF-NMRG-SMING-TYPES::Counter32. 

10.6.5 The column's format Statement

   The column's `format' statement, which need not be present, gets one
   argument which is used to give a hint as to how the value of an
   instance of this object might be displayed. See Section 3.12 for a
   description of format specifications. 

   The column's format specification overrides the format specification
   of the underlying type definition if both are present. 

10.6.6 The column's units Statement

   The column's `units' statement, which need not be present, gets one
   argument which is used to specify a textual definition of the units
   associated with this columnar object. 

   The column's units specification overrides the units specification
   of the underlying type definition if both are present. 

   The units specification has to be appropriate for values displayed
   according to the column's format specification if present. E.g., if
   the columnar object represents a frequency value of type Unsigned64
   measured in thousands of Hertz, the format specification should be
   `d-3' and the units specification should be `Hertz' or `Hz'. If the
   format specification would be omitted the units specification should
   be `Milli-Hertz' or `mHz'.  MIB Authors should pay attention to keep
   format and units specifications of type and object definitions
   synced. Application implementors MUST NOT implement units
   specifications without implementing format specifications. 


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10.6.7 The column's status Statement

   The column's `status' statement, which need not be present, gets one
   argument which is used to specify whether this columnar object
   definition is current or historic. The value `current' means that
   the definition is current and valid. The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated'
   also indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations. 

   Columnar objects SHOULD NOT be defined as `current' if their type is
   `deprecated' or `obsolete'. Similarly, they SHOULD NOT be defined as
   `deprecated' if their type is `obsolete'. Nevertheless, subsequent
   revisions of used type definition cannot be avoided, but SHOULD be
   taken into account in subsequent revisions of the local module. 

   If the `status' statement is omitted the status value `current' is
   implied. 

10.6.8 The column's description Statement

   The column's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of this columnar object. 

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this columnar object. 

10.6.9 The column's reference Statement

   The column's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   columnar objects, or some other document which provides additional
   information relevant to this columnar object. 

10.7 Usage Example

   Consider how one might define a table and its subordinates. (This
   example uses the RowStatus type defined in Section 14.2.) 

     scalar evalSlot {
       oid             eval.1;
       type            Integer32 (0..2147483647);
       access          readonly;
       description
               "The index number of the first unassigned entry in the


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                evaluation table, or the value of zero indicating that
                all entries are assigned.

                A management station should create new entries in the
                evaluation table using this algorithm:  first, issue a
                management protocol retrieval operation to determine the
                value of evalSlot; and, second, issue a management
                protocol set operation to create an instance of the
                evalStatus object setting its value to createAndGo(4) or
                createAndWait(5).  If this latter operation succeeds,
                then the management station may continue modifying the
                instances corresponding to the newly created conceptual
                row, without fear of collision with other management
                stations.";
     };

     table evalTable {
       oid             eval.2;
       description
               "The (conceptual) evaluation table.";
       reference
               "RFC 2578, 7.11.";

       row evalEntry {
         oid           evalTable.1;
         index         (evalIndex);
         create        (evalStatus);
         description
               "An entry (conceptual row) in the evaluation table.";

         column evalIndex {
           oid         evalEntry.1;
           type        Integer32 (1..2147483647);
           access      noaccess;
           description
               "The auxiliary variable used for identifying instances of
                the columnar objects in the evaluation table.";
         };

         column evalString {
           oid         evalEntry.2;
           type        DisplayString;
           access      readwrite;
           description
               "The string to evaluate.";
         };

         column evalValue {
           oid         evalEntry.3;


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           type        Integer32;
           access      readonly;
           default     0;
           description
               "The value when evalString was last evaluated, or zero if
                no such value is available.";
         };

         column evalStatus {
           oid         evalEntry.4;
           type        RowStatus;
           access      readwrite;
           default     active;
           description
               "The status column used for creating, modifying, and
                deleting instances of the columnar objects in the
                evaluation table.";
         };
       };
     };































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11. The notification Statement

   The `notification' statement is used to define a notification. It
   gets two arguments: a lower-case notification identifier and a
   statement block that holds detailed information in an obligatory
   order. 

   See the `notificationStatement' rule of the SMIng grammar (Appendix
   A) for the formal syntax of the `notification' statement. 

11.1 The notification's oid Statement

   The notification's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this notification. 

11.2 The notification's objects Statement

   The notification's `objects' statement, which need not be present,
   gets one argument which specifies an ordered sequence of objects by
   their identifiers to be emitted within this notification.  The list
   of objects has to be comma-separated and enclosed in parenthesis. 

   One and only one object instance for each occurrence of each object
   must be present, and in the specified order, in every instance of
   the notification.  If the same object occurs multiple times in a
   notification's `objects' statement, then an object instance is
   present for each of them.  An object specified in this sequence must
   not have an `access' statement argument of `noaccess'. 

   Note that an agent is allowed, at its own discretion, to append as
   many additional objects as it considers useful to the end of the
   notification (i.e., after the objects defined by the notification's
   `objects' statement if present). 

11.3 The notification's status Statement

   The notification's `status' statement, which need not be present,
   gets one argument which is used to specify whether this notification
   definition is current or historic. The value `current' means that
   the definition is current and valid.  The value `obsolete' means the
   definition is obsolete and should not be implemented and/or can be
   removed if previously implemented.  While the value `deprecated'
   also indicates an obsolete definition, it permits new/continued
   implementation in order to foster interoperability with
   older/existing implementations. 

   If the `status' statement is omitted the status value `current' is
   implied. 


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11.4 The notification's description Statement

   The notification's `description' statement, which must be present,
   gets one argument which is used to specify a high-level textual
   description of this notification. 

   It is RECOMMENDED to include all semantic definitions necessary for
   the implementation of this notification. In particular, it SHOULD be
   documented which instances of the objects mentioned in the `objects'
   statement should be contained within notifications of this type. 

11.5 The notification's reference Statement

   The notification's `reference' statement, which need not be present,
   gets one argument which is used to specify a textual cross-reference
   to some other document, either another module which defines related
   notifications, or some other document which provides additional
   information relevant to this notification. 

11.6 Usage Example

   Consider how a configuration change notification might be described: 

     node entityMIBTraps      { oid             entityMIB.2;      };

     node entityMIBTrapPrefix { oid             entityMIBTraps.0; };

     notification entConfigChange {
       oid             entityMIBTrapPrefix.1;
       description
               "An entConfigChange trap is sent when the value of
                entLastChangeTime changes. It can be utilized by an NMS
                to trigger logical/physical entity table maintenance
                polls.  An agent must not generate more than one
                entConfigChange 'trap-event' in a five second period,
                where a 'trap-event' is the transmission of a single
                trap PDU to a list of trap destinations.  If additional
                configuration changes occur within the five second
                'throttling' period then these trap-events should be
                suppressed by the agent. An NMS should periodically
                check the value of entLastChangeTime to detect any
                missed entConfigChange trap-events, e.g. due to
                throttling or transmission loss.";
     };







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12. The group Statement

   The `group' statement is used to define a group of arbitrary nodes
   in the object identifier tree.  It gets two arguments: a lower-case
   group identifier and a statement block that holds detailed group
   information in an obligatory order. 

   Note that the primary application of groups are compliance
   statements, although they might be referred in other formal or
   informal documents. 

   See the `groupStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `group' statement. 

12.1 The group's oid Statement

   The group's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this group. 

12.2 The group's members Statement

   The group's `members' statement, which must be present, gets one
   argument which specifies the list of nodes by their identifiers to
   be contained in this group. The list of nodes has to be
   comma-separated and enclosed in parenthesis. 

12.3 The group's status Statement

   The group's `status' statement, which need not be present, gets one
   argument which is used to specify whether this group definition is
   current or historic. The value `current' means that the definition
   is current and valid.  The value `obsolete' means the definition is
   obsolete and the group should no longer be used.  While the value
   `deprecated' also indicates an obsolete definition, it permits
   new/continued use of this group. 

   If the `status' statement is omitted the status value `current' is
   implied. 

12.4 The group's description Statement

   The group's `description' statement, which must be present, gets one
   argument which is used to specify a high-level textual description
   of this group.  It is RECOMMENDED to include any relation to other
   groups. 





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12.5 The group's reference Statement

   The group's `reference' statement, which need not be present, gets
   one argument which is used to specify a textual cross-reference to
   some other document, either another module which defines related
   groups, or some other document which provides additional information
   relevant to this group. 

12.6 Usage Example

   The snmpGroup, originally defined in [13], may be described as
   follows: 

     group snmpGroup {
       oid             snmpMIBGroups.8;
       objects         (snmpInPkts, snmpInBadVersions,
                        snmpInASNParseErrs,
                        snmpSilentDrops, snmpProxyDrops,
                        snmpEnableAuthenTraps);
       description
               "A collection of objects providing basic
                instrumentation and control of an agent.";
     };




























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13. The compliance Statement

   The `compliance' statement is used to define a set of compliance
   requirements, named a `compliance statement'. It gets two arguments:
   a lower-case compliance identifier and a statement block that holds
   detailed compliance information in an obligatory order. 

   See the `complianceStatement' rule of the SMIng grammar (Appendix A)
   for the formal syntax of the `compliance' statement. 

13.1 The compliance's oid Statement

   The compliance's `oid' statement, which must be present, gets one
   argument which specifies the object identifier value that is
   assigned to this compliance statement. 

13.2 The compliance's status Statement

   The compliance's `status' statement, which need not be present, gets
   one argument which is used to specify whether this compliance
   statement is current or historic. The value `current' means that the
   definition is current and valid. The value `obsolete' means the
   definition is obsolete and no longer specifies a valid definition of
   conformance.  While the value `deprecated' also indicates an
   obsolete definition, it permits new/continued use of the compliance
   specification. 

   If the `status' statement is omitted the status value `current' is
   implied. 

13.3 The compliance's description Statement

   The compliance's `description' statement, which must be present,
   gets one argument which is used to specify a high-level textual
   description of this compliance statement. 

13.4 The compliance's reference Statement

   The compliance's `reference' statement, which need not be present,
   gets one argument which is used to specify a textual cross-reference
   to some other document, either another module which defines related
   compliance statements, or some other document which provides
   additional information relevant to this compliance statement. 

13.5 The compliance's mandatory Statement

   The compliance's `mandatory' statement, which need not be present,
   gets one argument which is used to specify a comma-separated list of
   one or more groups (Section 12) of objects and/or notifications


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   enclosed in parenthesis. These groups are unconditionally mandatory
   for implementation. 

   If an agent claims compliance to a MIB module then it must implement
   each and every object and notification within each group listed the
   `mandatory' statement(s) of the compliance statement(s) of that
   module. 

13.6 The compliance's optional Statement

   The compliance's `optional' statement, which need not be present, is
   repeatedly used to name each group which is conditionally mandatory
   for compliance to the module. It can also be used to name
   unconditionally optional groups.  A group named in an `optional'
   statement MUST be absent from the correspondent `mandatory'
   statement. The `optional' statement gets two arguments: a lower-case
   group identifier and a statement block that holds detailed
   compliance information on that group. 

   Conditionally mandatory groups include those which are mandatory
   only if a particular protocol is implemented, or only if another
   group is implemented. The `description' statement specifies the
   conditions under which the group is conditionally mandatory. 

   A group which is named in neither a `mandatory' statement nor an
   `optional' statement, is unconditionally optional for compliance to
   the module. 

   See the `optionalStatement' rule of the SMIng grammar (Appendix A)
   for the formal syntax of the `optional' statement. 

13.6.1 The optional's description Statement

   The optional's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the conditions under which this group is
   conditionally mandatory or unconditionally optional. 

13.7 The compliance's refine Statement

   The compliance's `refine' statement, which need not be present, is
   repeatedly used to specify each object for which compliance has a
   refined requirement with respect to the module definition.  The
   object must be present in one of the conformance groups named in the
   correspondent `mandatory' or `optional' statements. The `refine'
   statement gets two arguments: a lower-case identifier of a scalar or
   columnar object and a statement block that holds detailed refinement
   information on that object. 



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   See the `refineStatement' rule of the SMIng grammar (Appendix A) for
   the formal syntax of the `refine' statement. 

13.7.1 The refine's type Statement

   The refine's `type' statement, which need not be present, gets one
   argument that is used to provide a refined type for the
   correspondent object. Type restrictions may be applied by appending
   subtyping information according to the rules of the base type.  See
   Section 3 for SMIng base types and their type restrictions. 

   Note that if a `type' and a `writetype' statement are both present
   then this type only applies when instances of the correspondent
   object are read. 

13.7.2 The refine's writetype Statement

   The refine's `writetype' statement, which need not be present, gets
   one argument that is used to provide a refined type for the
   correspondent object, only when instances of that object are
   written. Type restrictions may be applied by appending subtyping
   information according to the rules of the base type.  See Section 3
   for SMIng base types and their type restrictions. 

13.7.3 The refine's access Statement

   The refine's `access' statement, which need not be present, gets one
   argument that is used to specify the minimal level of access that
   the correspondent object must implement in the sense of its original
   `access' statement. Hence, the refine's `access' statement MUST NOT
   specify a greater level of access than is specified in the
   correspondent object definition. 

   An implementation is compliant if the level of access it provides is
   greater or equal to the minimal level in the refine's `access'
   statement and less or equal to the maximal level in the object's
   `access' statement. 

13.7.4 The refine's description Statement

   The refine's `description' statement, which must be present, gets
   one argument which is used to specify a high-level textual
   description of the refined compliance requirement. 

13.8 Usage Example

   The compliance statement contained in the SNMPv2-MIB, converted to
   SMIng: 



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     compliance snmpBasicCompliance {
       oid             snmpMIBCompliances.2;
       description
               "The compliance statement for SNMPv2 entities which
                implement the SNMPv2 MIB.";

       mandatory       (snmpGroup, snmpSetGroup, systemGroup,
                        snmpBasicNotificationsGroup);

       optional snmpCommunityGroup {
         description
               "This group is mandatory for SNMPv2 entities which
                support community-based authentication.";
       };
     };




































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14. SMIng Core Modules

   MIB modules, either SMIv1, SMIv2 or SMIng, are built on top of some
   core definitions. These core definitions are imported from some
   "well-defined" core modules. In case of SMIng, there are two core
   modules: 

   1.  IRTF-NMRG-SMING, which defines a special node, named
       `zeroDotZero' that may be used by objects of type
       `ObjectIdentifier' as a null value, and a core set of 18 nodes
       near the root of the object identifier tree. Only some of those
       core nodes are significant for the Internet management and have
       been described in Section 2.2. 

   2.  IRTF-NMRG-SMING-TYPES, which defines SMIng data types. Regarding
       to their origin, these types can be divided into two groups:
       those being ASN.1 application types defined as SMIv2 core types
       [2] and those being textual conventions in SMIv2 [3]. For use in
       SMIng, there is no need to care about these differences, though
       it might be useful in SNMP applications, to know that some types
       are distinguishable "on the wire" and others are not. 

   3.  IRTF-NMRG-SMING-EXTENSIONS, which defines proposed SMIng
       extensions. At this moment, there is only one extension, the
       `agentcaps' statement. See Section 16 for details on extensions. 

14.1 IRTF-NMRG-SMING

   module IRTF-NMRG-SMING {

   //
   // $RCSfile$
   // $Revision: 8676 $
   // $Author: ispringer $
   // $Date: 2008-01-18 07:11:17 +0800 (Fri, 18 Jan 2008) $
   //

       organization    "IRTF Network Management Research Group (NMRG),
                        Network Management Group, TU Braunschweig";

       contact         "        Frank Strauss

                        Postal: TU Braunschweig
                                Bueltenweg 74/75
                                38106 Braunschweig
                                Germany

                         Phone: +49 531 391-3266
                         EMail: strauss@ibr.cs.tu-bs.de";


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       description     "Core node definitions for SMIng.";

       revision {
           date        "2000-02-13";
           description "SMIng grammar dropped module identity objects.";
       };

       revision {
           date        "1999-05-07";
           description "Initial Revision.";
       };

       node ccitt                          { oid 0;                };

       node   zeroDotZero {
           oid         0.0;
           description "A value used for null identifiers.";
       };

       node iso                            { oid 1;                };
       node   org                          { oid iso.3;            };
       node     dod                        { oid org.6;            };
       node       internet                 { oid dod.1;            };
       node         directory              { oid internet.1;       };
       node         mgmt                   { oid internet.2;       };
       node           mib-2                { oid mgmt.1;           };
       node             transmission       { oid mib-2.10;         };
       node         experimental           { oid internet.3;       };
       node         private                { oid internet.4;       };
       node           enterprises          { oid private.1;        };
       node         security               { oid internet.5;       };
       node         snmpV2                 { oid internet.6;       };
       node           snmpDomains          { oid snmpV2.1;         };
       node           snmpProxys           { oid snmpV2.2;         };
       node           snmpModules          { oid snmpV2.3;         };

       node joint-iso-ccitt                { oid 2;                };

   };

14.2 IRTF-NMRG-SMING-TYPES

   module IRTF-NMRG-SMING-TYPES {

   //
   // $RCSfile$
   // $Revision: 8676 $
   // $Author: ispringer $
   // $Date: 2008-01-18 07:11:17 +0800 (Fri, 18 Jan 2008) $


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   //

       organization    "IRTF Network Management Research Group (NMRG),
                        Network Management Group, TU Braunschweig";

       contact         "        Frank Strauss

                        Postal: TU Braunschweig
                                Bueltenweg 74/75
                                38106 Braunschweig
                                Germany

                         Phone: +49 531 391-3266
                         EMail: strauss@ibr.cs.tu-bs.de";

       description     "Core type definitions for SMIng.";

       revision {
           date        "2000-02-13";
           description "SMIng grammar dropped module identity objects.";
       };

       revision {
           date        "1999-05-07";
           description "Initial Revision.";
       };

       typedef Gauge32 {
           type        Unsigned32;
           description
              "The Gauge32 type represents a non-negative integer,
               which may increase or decrease, but shall never
               exceed a maximum value, nor fall below a minimum
               value.  The maximum value can not be greater than
               2^32-1 (4294967295 decimal), and the minimum value
               can not be smaller than 0.  The value of a Gauge32
               has its maximum value whenever the information
               being modeled is greater than or equal to its
               maximum value, and has its minimum value whenever
               the information being modeled is smaller than or
               equal to its minimum value.  If the information
               being modeled subsequently decreases below
               (increases above) the maximum (minimum) value, the
               Gauge32 also decreases (increases).  (Note that
               despite of the use of the term `latched' in the
               original definition of this type, it does not
               become `stuck' at its maximum or minimum value.)";
           reference
              "RFC 2578, Sections 2. and 7.1.7.";


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       };

       typedef Counter32 {
           type        Unsigned32;
           description
              "The Counter32 type represents a non-negative integer
               which monotonically increases until it reaches a
               maximum value of 2^32-1 (4294967295 decimal), when it
               wraps around and starts increasing again from zero.

               Counters have no defined `initial' value, and thus, a
               single value of a Counter has (in general) no
               information content.  Discontinuities in the
               monotonically increasing value normally occur at
               re-initialization of the management system, and at
               other times as specified in the description of an
               object using this type.  If such other times can
               occur, for example, the creation of an object
               instance at times other than re-initialization, then
               a corresponding object should be defined, with an
               appropriate type, to indicate the last discontinuity.
               Examples of appropriate types include: TimeStamp,
               DateAndTime or TimeTicks (other types defined in this
               module).

               The value of the access statement for objects with a
               type value of Counter32 should be either `readonly'
               or `notifyonly'.

               A default statement should not be used for objects
               with a type value of Counter32.";
           reference
              "RFC 2578, Sections 2. and 7.1.6.";
       };

       typedef Gauge64 {
           type        Unsigned64;
           description
              "The Gauge64 type represents a non-negative integer,
               which may increase or decrease, but shall never
               exceed a maximum value, nor fall below a minimum
               value.  The maximum value can not be greater than
               2^64-1 (18446744073709551615), and the minimum value
               can not be smaller than 0.  The value of a Gauge64
               has its maximum value whenever the information
               being modeled is greater than or equal to its
               maximum value, and has its minimum value whenever
               the information being modeled is smaller than or
               equal to its minimum value.  If the information


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               being modeled subsequently decreases below
               (increases above) the maximum (minimum) value, the
               Gauge64 also decreases (increases).  (Note that
               despite of the use of the term `latched' in the
               original definition of this type, it does not
               become `stuck' at its maximum or minimum value.)";
       };

       typedef Counter64 {
           type        Unsigned64;
           description
              "The Counter64 type represents a non-negative integer
               which monotonically increases until it reaches a
               maximum value of 2^64-1 (18446744073709551615), when
               it wraps around and starts increasing again from zero.

               Counters have no defined `initial' value, and thus, a
               single value of a Counter has (in general) no
               information content.  Discontinuities in the
               monotonically increasing value normally occur at
               re-initialization of the management system, and at
               other times as specified in the description of an
               object using this type.  If such other times can
               occur, for example, the creation of an object
               instance at times other than re-initialization, then
               a corresponding object should be defined, with an
               appropriate type, to indicate the last discontinuity.
               Examples of appropriate types include: TimeStamp,
               DateAndTime or TimeTicks (other types defined in this
               module).

               The value of the access statement for objects with a
               type value of Counter64 should be either `readonly'
               or `notifyonly'.

               A default statement should not be used for objects
               with a type value of Counter64.";
           reference
              "RFC 2578, Sections 2. and 7.1.10.";
       };

       typedef Opaque {
           type        OctetString;
           description
              "The Opaque type is provided solely for
               backward-compatibility, and shall not be used for
               newly-defined object types.

               The Opaque type supports the capability to pass


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               arbitrary ASN.1 syntax.  A value is encoded using
               the ASN.1 Basic Encoding Rules into a string of
               octets.  This, in turn, is encoded as an
               OctetString, in effect `double-wrapping' the
               original ASN.1 value.

               Note that a conforming implementation need only be
               able to accept and recognize opaquely-encoded data.
               It need not be able to unwrap the data and then
               interpret its contents.

               A requirement on `standard' MIB modules is that no
               object may have a type value of Opaque.";
           reference
              "RFC 2578, Sections 2. and 7.1.9.";
       };

       typedef IpAddress {
           type        OctetString (4);
           status      deprecated;
           description
              "******* THIS TYPE DEFINITION IS DEPRECATED *******

               The IpAddress type represents a 32-bit internet
               IPv4 address.  It is represented as an OctetString
               of length 4, in network byte-order.

               Note that the IpAddress type is present for
               historical reasons. IPv4 and IPv6 addresses should
               be represented using the IpAddr type. Generic
               Network addresses should be represented using a
               pair of TDomain and TAddress types (all defined in
               this module).";
           reference
              "RFC 2578, Sections 2. and 7.1.5.";
       };

       typedef TimeTicks {
           type        Unsigned32;
           description
              "The TimeTicks type represents a non-negative
               integer which represents the time, modulo 2^32
               (4294967296 decimal), in hundredths of a second
               between two epochs.  When objects are defined which
               use this type, the description of the object
               identifies both of the reference epochs.

               For example, the TimeStamp type (defined in this
               module) is based on the TimeTicks type.


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               With a TimeStamp, the first reference epoch is
               defined as the time when SNMPv2-MIB::sysUpTime was
               zero, and the second reference epoch is defined as
               the current value of sysUpTime.

               The TimeTicks type should not be sub-typed.";
           reference
              "RFC 2578, Sections 2. and 7.1.8.";
       };

       //
       //  The following type definitions are plain
       //  conversions of the textual conventions from
       //  the SNMPv2-TC module (RFC 2579).
       //

       typedef DisplayString {
           type        OctetString (0..255);
           format      "255a";
           description
           "Represents textual information taken from the NVT ASCII
            character set, as defined in pages 4, 10-11 of RFC 854.

            To summarize RFC 854, the NVT ASCII repertoire specifies:

             - the use of character codes 0-127 (decimal)

             - the graphics characters (32-126) are interpreted as
               US ASCII

             - NUL, LF, CR, BEL, BS, HT, VT and FF have the special
               meanings specified in RFC 854

             - the other 25 codes have no standard interpretation

             - the sequence 'CR LF' means newline

             - the sequence 'CR NUL' means carriage-return

             - an 'LF' not preceded by a 'CR' means moving to the
               same column on the next line.

             - the sequence 'CR x' for any x other than LF or NUL is
               illegal.  (Note that this also means that a string may
               end with either 'CR LF' or 'CR NUL', but not with CR.)

            Any object defined using this syntax may not exceed 255
            characters in length.";
       };


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       typedef PhysAddress {
           type        OctetString;
           format      "1x:";
           description
           "Represents media- or physical-level addresses.";
       };

       typedef MacAddress {
           type        OctetString (6);
           format      "1x:";
           description
           "Represents an 802 MAC address represented in the
            `canonical' order defined by IEEE 802.1a, i.e., as if it
            were transmitted least significant bit first, even though
            802.5 (in contrast to other 802.x protocols) requires MAC
            addresses to be transmitted most significant bit first.";
       };

       typedef TruthValue {
           type        Enumeration (true(1), false(2));
           description
           "Represents a boolean value.";
       };

       typedef TestAndIncr {
           type        Integer32 (0..2147483647);
           description
           "Represents integer-valued information used for atomic
            operations.  When the management protocol is used to specify
            that an object instance having this syntax is to be
            modified, the new value supplied via the management protocol
            must precisely match the value presently held by the
            instance.  If not, the management protocol set operation
            fails with an error of `inconsistentValue'.  Otherwise, if
            the current value is the maximum value of 2^31-1 (2147483647
            decimal), then the value held by the instance is wrapped to
            zero; otherwise, the value held by the instance is
            incremented by one.  (Note that regardless of whether the
            management protocol set operation succeeds, the variable-
            binding in the request and response PDUs are identical.)

            The value of the ACCESS clause for objects having this
            syntax is either `read-write' or `read-create'.  When an
            instance of a columnar object having this syntax is created,
            any value may be supplied via the management protocol.

            When the network management portion of the system is re-
            initialized, the value of every object instance having this
            syntax must either be incremented from its value prior to


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            the re-initialization, or (if the value prior to the re-
            initialization is unknown) be set to a pseudo-randomly
            generated value.";
       };

       typedef AutonomousType {
           type        ObjectIdentifier;
           description
           "Represents an independently extensible type identification
            value.  It may, for example, indicate a particular sub-tree
            with further MIB definitions, or define a particular type of
            protocol or hardware.";
       };

       typedef InstancePointer {
           type        ObjectIdentifier;
           status      obsolete;
           description
           "A pointer to either a specific instance of a MIB object or
            a conceptual row of a MIB table in the managed device.  In
            the latter case, by convention, it is the name of the
            particular instance of the first accessible columnar object
            in the conceptual row.

            The two uses of this textual convention are replaced by
            VariablePointer and RowPointer, respectively.";
       };

       typedef VariablePointer {
           type        ObjectIdentifier;
           description
           "A pointer to a specific object instance.  For example,
            sysContact.0 or ifInOctets.3.";
       };

       typedef RowPointer {
           type        ObjectIdentifier;
           description
           "Represents a pointer to a conceptual row.  The value is the
            name of the instance of the first accessible columnar object
            in the conceptual row.

            For example, ifIndex.3 would point to the 3rd row in the
            ifTable (note that if ifIndex were not-accessible, then
            ifDescr.3 would be used instead).";
       };

       typedef RowStatus {
           type        Enumeration (active(1), notInService(2),


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                           notReady(3), createAndGo(4),
                           createAndWait(5), destroy(6));
           description
           "The RowStatus textual convention is used to manage the
            creation and deletion of conceptual rows, and is used as the
            value of the SYNTAX clause for the status column of a
            conceptual row (as described in Section 7.7.1 of [2].)

            The status column has six defined values:

                - `active', which indicates that the conceptual row is
                available for use by the managed device;

                - `notInService', which indicates that the conceptual
                row exists in the agent, but is unavailable for use by
                the managed device (see NOTE below);

                - `notReady', which indicates that the conceptual row
                exists in the agent, but is missing information
                necessary in order to be available for use by the
                managed device;

                - `createAndGo', which is supplied by a management
                station wishing to create a new instance of a
                conceptual row and to have its status automatically set
                to active, making it available for use by the managed
                device;

                - `createAndWait', which is supplied by a management
                station wishing to create a new instance of a
                conceptual row (but not make it available for use by
                the managed device); and,

                - `destroy', which is supplied by a management station
                wishing to delete all of the instances associated with
                an existing conceptual row.

            Whereas five of the six values (all except `notReady') may
            be specified in a management protocol set operation, only
            three values will be returned in response to a management
            protocol retrieval operation: `notReady', `notInService' or
            `active'.  That is, when queried, an existing conceptual row
            has only three states: it is either available for use by the
            managed device (the status column has value `active'); it is
            not available for use by the managed device, though the


            agent has sufficient information to make it so (the status
            column has value `notInService'); or, it is not available


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            for use by the managed device, and an attempt to make it so
            would fail because the agent has insufficient information
            (the state column has value `notReady').

                                    NOTE WELL

                This textual convention may be used for a MIB table,
                irrespective of whether the values of that table's
                conceptual rows are able to be modified while it is
                active, or whether its conceptual rows must be taken
                out of service in order to be modified.  That is, it is
                the responsibility of the DESCRIPTION clause of the
                status column to specify whether the status column must
                not be `active' in order for the value of some other
                column of the same conceptual row to be modified.  If
                such a specification is made, affected columns may be
                changed by an SNMP set PDU if the RowStatus would not
                be equal to `active' either immediately before or after
                processing the PDU.  In other words, if the PDU also
                contained a varbind that would change the RowStatus
                value, the column in question may be changed if the
                RowStatus was not equal to `active' as the PDU was
                received, or if the varbind sets the status to a value
                other than 'active'.

            Also note that whenever any elements of a row exist, the
            RowStatus column must also exist.


            To summarize the effect of having a conceptual row with a
            status column having a SYNTAX clause value of RowStatus,
            consider the following state diagram:

                                            STATE
                 +--------------+-----------+-------------+-------------
                 |      A       |     B     |      C      |      D
                 |              |status col.|status column|
                 |status column |    is     |      is     |status column
       ACTION    |does not exist|  notReady | notInService|  is active
   --------------+--------------+-----------+-------------+-------------
   set status    |noError    ->D|inconsist- |inconsistent-|inconsistent-
   column to     |       or     |   entValue|        Value|        Value
   createAndGo   |inconsistent- |           |             |
                 |         Value|           |             |
   --------------+--------------+-----------+-------------+-------------
   set status    |noError  see 1|inconsist- |inconsistent-|inconsistent-
   column to     |       or     |   entValue|        Value|        Value
   createAndWait |wrongValue    |           |             |
   --------------+--------------+-----------+-------------+-------------


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   set status    |inconsistent- |inconsist- |noError      |noError
   column to     |         Value|   entValue|             |
   active        |              |           |             |
                 |              |     or    |             |
                 |              |           |             |
                 |              |see 2   ->D|see 8     ->D|          ->D
   --------------+--------------+-----------+-------------+-------------
   set status    |inconsistent- |inconsist- |noError      |noError   ->C
   column to     |         Value|   entValue|             |
   notInService  |              |           |             |
                 |              |     or    |             |      or
                 |              |           |             |
                 |              |see 3   ->C|          ->C|see 6
   --------------+--------------+-----------+-------------+-------------
   set status    |noError       |noError    |noError      |noError   ->A
   column to     |              |           |             |      or
   destroy       |           ->A|        ->A|          ->A|see 7
   --------------+--------------+-----------+-------------+-------------
   set any other |see 4         |noError    |noError      |see 5
   column to some|              |           |             |
   value         |              |      see 1|          ->C|          ->D
   --------------+--------------+-----------+-------------+-------------

            (1) goto B or C, depending on information available to the


            agent.

            (2) if other variable bindings included in the same PDU,
            provide values for all columns which are missing but
            required, then return noError and goto D.

            (3) if other variable bindings included in the same PDU,
            provide values for all columns which are missing but
            required, then return noError and goto C.

            (4) at the discretion of the agent, the return value may be
            either:

                inconsistentName: because the agent does not choose to
                create such an instance when the corresponding
                RowStatus instance does not exist, or

                inconsistentValue: if the supplied value is
                inconsistent with the state of some other MIB object's
                value, or

                noError: because the agent chooses to create the
                instance.


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            If noError is returned, then the instance of the status
            column must also be created, and the new state is B or C,
            depending on the information available to the agent.  If
            inconsistentName or inconsistentValue is returned, the row
            remains in state A.

            (5) depending on the MIB definition for the column/table,
            either noError or inconsistentValue may be returned.

            (6) the return value can indicate one of the following
            errors:

                wrongValue: because the agent does not support
                createAndWait, or

                inconsistentValue: because the agent is unable to take
                the row out of service at this time, perhaps because it
                is in use and cannot be de-activated.

            (7) the return value can indicate the following error:


                inconsistentValue: because the agent is unable to
                remove the row at this time, perhaps because it is in
                use and cannot be de-activated.

            NOTE: Other processing of the set request may result in a
            response other than noError being returned, e.g.,
            wrongValue, noCreation, etc.

                             Conceptual Row Creation

            There are four potential interactions when creating a
            conceptual row: selecting an instance-identifier which is
            not in use; creating the conceptual row; initializing any
            objects for which the agent does not supply a default; and,
            making the conceptual row available for use by the managed
            device.

            Interaction 1: Selecting an Instance-Identifier

            The algorithm used to select an instance-identifier varies
            for each conceptual row.  In some cases, the instance-
            identifier is semantically significant, e.g., the
            destination address of a route, and a management station
            selects the instance-identifier according to the semantics.

            In other cases, the instance-identifier is used solely to
            distinguish conceptual rows, and a management station


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            without specific knowledge of the conceptual row might
            examine the instances present in order to determine an
            unused instance-identifier.  (This approach may be used, but
            it is often highly sub-optimal; however, it is also a
            questionable practice for a naive management station to
            attempt conceptual row creation.)

            Alternately, the MIB module which defines the conceptual row
            might provide one or more objects which provide assistance
            in determining an unused instance-identifier.  For example,
            if the conceptual row is indexed by an integer-value, then
            an object having an integer-valued SYNTAX clause might be
            defined for such a purpose, allowing a management station to
            issue a management protocol retrieval operation.  In order
            to avoid unnecessary collisions between competing management
            stations, `adjacent' retrievals of this object should be
            different.


            Finally, the management station could select a pseudo-random
            number to use as the index.  In the event that this index
            was already in use and an inconsistentValue was returned in
            response to the management protocol set operation, the
            management station should simply select a new pseudo-random
            number and retry the operation.

            A MIB designer should choose between the two latter
            algorithms based on the size of the table (and therefore the
            efficiency of each algorithm).  For tables in which a large
            number of entries are expected, it is recommended that a MIB
            object be defined that returns an acceptable index for
            creation.  For tables with small numbers of entries, it is
            recommended that the latter pseudo-random index mechanism be
            used.

            Interaction 2: Creating the Conceptual Row

            Once an unused instance-identifier has been selected, the
            management station determines if it wishes to create and
            activate the conceptual row in one transaction or in a
            negotiated set of interactions.

            Interaction 2a: Creating and Activating the Conceptual Row

            The management station must first determine the column
            requirements, i.e., it must determine those columns for
            which it must or must not provide values.  Depending on the
            complexity of the table and the management station's
            knowledge of the agent's capabilities, this determination


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            can be made locally by the management station.  Alternately,
            the management station issues a management protocol get
            operation to examine all columns in the conceptual row that
            it wishes to create.  In response, for each column, there
            are three possible outcomes:

                - a value is returned, indicating that some other
                management station has already created this conceptual
                row.  We return to interaction 1.


                - the exception `noSuchInstance' is returned,
                indicating that the agent implements the object-type
                associated with this column, and that this column in at
                least one conceptual row would be accessible in the MIB
                view used by the retrieval were it to exist. For those
                columns to which the agent provides read-create access,
                the `noSuchInstance' exception tells the management
                station that it should supply a value for this column
                when the conceptual row is to be created.

                - the exception `noSuchObject' is returned, indicating
                that the agent does not implement the object-type
                associated with this column or that there is no
                conceptual row for which this column would be
                accessible in the MIB view used by the retrieval.  As
                such, the management station can not issue any
                management protocol set operations to create an
                instance of this column.

            Once the column requirements have been determined, a
            management protocol set operation is accordingly issued.
            This operation also sets the new instance of the status
            column to `createAndGo'.

            When the agent processes the set operation, it verifies that
            it has sufficient information to make the conceptual row
            available for use by the managed device.  The information
            available to the agent is provided by two sources: the
            management protocol set operation which creates the
            conceptual row, and, implementation-specific defaults
            supplied by the agent (note that an agent must provide
            implementation-specific defaults for at least those objects
            which it implements as read-only).  If there is sufficient
            information available, then the conceptual row is created, a
            `noError' response is returned, the status column is set to
            `active', and no further interactions are necessary (i.e.,
            interactions 3 and 4 are skipped).  If there is insufficient
            information, then the conceptual row is not created, and the


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            set operation fails with an error of `inconsistentValue'.
            On this error, the management station can issue a management
            protocol retrieval operation to determine if this was
            because it failed to specify a value for a required column,
            or, because the selected instance of the status column
            already existed.  In the latter case, we return to
            interaction 1.  In the former case, the management station


            can re-issue the set operation with the additional
            information, or begin interaction 2 again using
            `createAndWait' in order to negotiate creation of the
            conceptual row.

                                    NOTE WELL

                Regardless of the method used to determine the column
                requirements, it is possible that the management
                station might deem a column necessary when, in fact,
                the agent will not allow that particular columnar
                instance to be created or written.  In this case, the
                management protocol set operation will fail with an
                error such as `noCreation' or `notWritable'.  In this
                case, the management station decides whether it needs
                to be able to set a value for that particular columnar
                instance.  If not, the management station re-issues the
                management protocol set operation, but without setting
                a value for that particular columnar instance;
                otherwise, the management station aborts the row
                creation algorithm.


            Interaction 2b: Negotiating the Creation of the Conceptual
            Row

            The management station issues a management protocol set
            operation which sets the desired instance of the status
            column to `createAndWait'.  If the agent is unwilling to
            process a request of this sort, the set operation fails with
            an error of `wrongValue'.  (As a consequence, such an agent
            must be prepared to accept a single management protocol set
            operation, i.e., interaction 2a above, containing all of the
            columns indicated by its column requirements.) Otherwise,
            the conceptual row is created, a `noError' response is
            returned, and the status column is immediately set to either
            `notInService' or `notReady', depending on whether it has
            sufficient information to make the conceptual row available
            for use by the managed device.  If there is sufficient
            information available, then the status column is set to


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            `notInService'; otherwise, if there is insufficient
            information, then the status column is set to `notReady'.
            Regardless, we proceed to interaction 3.

            Interaction 3: Initializing non-defaulted Objects

            The management station must now determine the column
            requirements.  It issues a management protocol get operation
            to examine all columns in the created conceptual row.  In
            the response, for each column, there are three possible
            outcomes:

                - a value is returned, indicating that the agent
                implements the object-type associated with this column
                and had sufficient information to provide a value.  For
                those columns to which the agent provides read-create
                access (and for which the agent allows their values to
                be changed after their creation), a value return tells
                the management station that it may issue additional
                management protocol set operations, if it desires, in
                order to change the value associated with this column.


                - the exception `noSuchInstance' is returned,
                indicating that the agent implements the object-type
                associated with this column, and that this column in at
                least one conceptual row would be accessible in the MIB
                view used by the retrieval were it to exist. However,
                the agent does not have sufficient information to
                provide a value, and until a value is provided, the
                conceptual row may not be made available for use by the
                managed device.  For those columns to which the agent
                provides read-create access, the `noSuchInstance'
                exception tells the management station that it must
                issue additional management protocol set operations, in
                order to provide a value associated with this column.

                - the exception `noSuchObject' is returned, indicating
                that the agent does not implement the object-type
                associated with this column or that there is no
                conceptual row for which this column would be
                accessible in the MIB view used by the retrieval.  As
                such, the management station can not issue any
                management protocol set operations to create an
                instance of this column.

            If the value associated with the status column is
            `notReady', then the management station must first deal with
            all `noSuchInstance' columns, if any.  Having done so, the


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            value of the status column becomes `notInService', and we
            proceed to interaction 4.

            Interaction 4: Making the Conceptual Row Available

            Once the management station is satisfied with the values
            associated with the columns of the conceptual row, it issues
            a management protocol set operation to set the status column
            to `active'.  If the agent has sufficient information to
            make the conceptual row available for use by the managed
            device, the management protocol set operation succeeds (a
            `noError' response is returned).  Otherwise, the management
            protocol set operation fails with an error of
            `inconsistentValue'.


                                    NOTE WELL

                A conceptual row having a status column with value
                `notInService' or `notReady' is unavailable to the
                managed device.  As such, it is possible for the
                managed device to create its own instances during the
                time between the management protocol set operation
                which sets the status column to `createAndWait' and the
                management protocol set operation which sets the status
                column to `active'.  In this case, when the management
                protocol set operation is issued to set the status
                column to `active', the values held in the agent
                supersede those used by the managed device.

            If the management station is prevented from setting the
            status column to `active' (e.g., due to management station
            or network failure) the conceptual row will be left in the
            `notInService' or `notReady' state, consuming resources
            indefinitely.  The agent must detect conceptual rows that
            have been in either state for an abnormally long period of
            time and remove them.  It is the responsibility of the
            DESCRIPTION clause of the status column to indicate what an
            abnormally long period of time would be.  This period of
            time should be long enough to allow for human response time
            (including `think time') between the creation of the
            conceptual row and the setting of the status to `active'.
            In the absence of such information in the DESCRIPTION
            clause,
            it is suggested that this period be approximately 5 minutes
            in length.  This removal action applies not only to newly-
            created rows, but also to previously active rows which are
            set to, and left in, the notInService state for a prolonged
            period exceeding that which is considered normal for such a


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            conceptual row.


                            Conceptual Row Suspension

            When a conceptual row is `active', the management station
            may issue a management protocol set operation which sets the
            instance of the status column to `notInService'.  If the
            agent is unwilling to do so, the set operation fails with an
            error of `wrongValue' or `inconsistentValue'.
            Otherwise, the conceptual row is taken out of service, and a
            `noError' response is returned.  It is the responsibility of
            the DESCRIPTION clause of the status column to indicate
            under what circumstances the status column should be taken
            out of service (e.g., in order for the value of some other
            column of the same conceptual row to be modified).

                             Conceptual Row Deletion

            For deletion of conceptual rows, a management protocol set
            operation is issued which sets the instance of the status
            column to `destroy'.  This request may be made regardless of
            the current value of the status column (e.g., it is possible
            to delete conceptual rows which are either `notReady',
            `notInService' or `active'.) If the operation succeeds, then
            all instances associated with the conceptual row are
            immediately removed.";
       };

       typedef TimeStamp {
           type        TimeTicks;
           description
           "The value of the sysUpTime object at which a specific
            occurrence happened.  The specific occurrence must be
            defined in the description of any object defined using this
            type.  When the specific occurrence occurred prior to the
            last time sysUpTime was zero, then the TimeStamp value is
            zero.  Note that this requires all TimeStamp values to be
            reset to zero when the value of sysUpTime reaches 497+ days
            and wraps around to zero.";
       };

       typedef TimeInterval {
           type        Integer32 (0..2147483647);
           description
           "A period of time, measured in units of 0.01 seconds.";
       };

       typedef DateAndTime {


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           type        OctetString (8 | 11);
           format      "2d-1d-1d,1d:1d:1d.1d,1a1d:1d";
           description
           "A date-time specification.

            field  octets  contents                  range
            -----  ------  --------                  -----
             1      1-2   year*                     0..65536
             2       3    month                     1..12
             3       4    day                       1..31
             4       5    hour                      0..23
             5       6    minutes                   0..59
             6       7    seconds                   0..60
                          (use 60 for leap-second)
             7       8    deci-seconds              0..9
             8       9    direction from UTC        '+' / '-'
             9      10    hours from UTC*           0..13
            10      11    minutes from UTC          0..59

            * Notes:
            - the value of year is in big-endian encoding
            - daylight saving time in New Zealand is +13

            For example, Tuesday May 26, 1992 at 1:30:15 PM EDT would be
            displayed as:

                            1992-5-26,13:30:15.0,-4:0

            Note that if only local time is known, then timezone
            information (fields 8-10) is not present.";
       };

       typedef StorageType {
           type        Enumeration (other(1), volatile(2),
                           nonVolatile(3), permanent(4),
                           readOnly(5));
           description
           "Describes the memory realization of a conceptual row.  A
            row which is volatile(2) is lost upon reboot.  A row which
            is either nonVolatile(3), permanent(4) or readOnly(5), is
            backed up by stable storage.  A row which is permanent(4)
            can be changed but not deleted.  A row which is readOnly(5)
            cannot be changed nor deleted.

            If the value of an object with this syntax is either
            permanent(4) or readOnly(5), it cannot be modified.
            Conversely, if the value is either other(1), volatile(2) or
            nonVolatile(3), it cannot be modified to be permanent(4) or
            readOnly(5).  (All illegal modifications result in a


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            'wrongValue' error.)

            Every usage of this textual convention is required to
            specify the columnar objects which a permanent(4) row must
            at a minimum allow to be writable.";
       };

       typedef TDomain {
           type        ObjectIdentifier;
           description
           "Denotes a kind of transport service.

            Some possible values, such as snmpUDPDomain, are defined in
            'Transport Mappings for Version 2 of the Simple Network
            Management Protocol (SNMPv2)'.";
       };

       typedef TAddress {
           type        OctetString (1..255);
           description
           "Denotes a transport service address.

            For snmpUDPDomain, a TAddress is 6 octets long, the initial
            4 octets containing the IP-address in network-byte order and
            the last 2 containing the UDP port in network-byte order.
            Cosult 'Transport Mappings for Version 2 of the Simple
            Network Management Protocol (SNMPv2)' for further
            information on snmpUDPDomain.";
       };

   };

14.3 IRTF-NMRG-SMING-EXTENSIONS

   module IRTF-NMRG-SMING-EXTENSIONS {

   //
   // $RCSfile$
   // $Revision: 8676 $
   // $Author: ispringer $
   // $Date: 2008-01-18 07:11:17 +0800 (Fri, 18 Jan 2008) $
   //

       organization    "IRTF Network Management Research Group (NMRG),
                        Network Management Group, TU Braunschweig";

       contact         "        Frank Strauss

                        Postal: TU Braunschweig


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                                Bueltenweg 74/75
                                38106 Braunschweig
                                Germany

                         Phone: +49 531 391-3266
                         EMail: strauss@ibr.cs.tu-bs.de";

       description     "Core extension definitions for SMIng.";

       revision {
           date        "2000-02-13";
           description "SMIng grammar dropped module identity objects.";
       };

       revision {
           date        "1999-05-07";
           description "Initial Revision.";
       };

       extension agentcaps {
           status      current;
           description
                 "The agentcaps extension statement is used to describe
                  an agent's deviation from the compliance statements
                  of the modules it implements. It is designed to be
                  compatible with the SMIv2 AGENT-CAPABILITIES macro.

                  The agentcaps extension statement should only be used
                  in the statement body of a module that does not
                  contain any other type or node definitions that do not
                  correspond to an agent implementation.";
           reference
                 "RFC 2580, Section 6 describes the SMIv2
                  compatible AGENT-CAPABILITIES macro.";
           abnf
                 "agentcapsStatement = 'agentcaps' sep lcIdentifier
                                       optsep '{' stmtsep
                                         oidStatement stmtsep
                                         releaseStatement stmtsep
                                         *1(statusStatement stmtsep)
                                         descriptionStatement stmtsep
                                         *1(referenceStatement stmtsep)
                                         *(includesStatement stmtsep)
                                       '}' optsep ';'

                  includesStatement  = 'includes' sep qlcIdentifier
                                       optsep '{' stmtsep
                                         *(variationStatement stmtsep)
                                       '}' optsep ';'


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                  variationStatement = 'variation' sep qlcIdentifier
                                       optsep '{' stmtsep
                                         typeStatement stmtsep
                                         writetypeStatement stmtsep
                                         accessStatement stmtsep
                                         createStatement stmtsep
                                       '}' optsep ';'
                  ";
       };

   };








































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15. Extending a Module

   As experience is gained with a module, it may be desirable to revise
   that module.  However, changes are not allowed if they have any
   potential to cause interoperability problems between an
   implementation using an original specification and an implementation
   using an updated specification(s). 

   For any change, some statements near the top of the module MUST be
   updated to include information about the revision: specifically, a
   new `revision' statement (Section 5.6) must be included in front of
   the `revision' statements. Furthermore, any necessary changes MUST
   be applied to other statements, including the `organization' and
   `contact' statements (Section 5.2, Section 5.3). 

   Note that any definition contained in a module is available to be
   imported by any other module, and is referenced in an `import'
   statement via the module name.  Thus, a module name MUST NOT be
   changed. Specifically, the module name (e.g., `FIZBIN-MIB' in the
   example of Section 5.8) MUST NOT be changed when revising a module
   (except to correct typographical errors), and definitions MUST NOT
   be moved from one module to another. 

   Also note, that obsolete definitions MUST NOT be removed from
   modules since their descriptors may still be referenced by other
   modules, and the object identifiers used to name them MUST never be
   re-assigned. 

   A definition may be revised in any of the following ways: 

   o  In `typedef', `scalar' and `column' statement blocks, a `type'
      statement containing an `Enumeration' or `Bits' type may have new
      named numbers added. 

   o  In `typedef', `scalar' and `column' statement blocks, the value
      of a `type' statement may be replaced by another type if the new
      type is derived (directly or indirectly) from the same base type,
      has the same set of values, and has identical semantics. 

   o  In any statement block, a `status' statement value of `current'
      (or a missing `status' statement) may be revised as `deprecated'
      or `obsolete'.  Similarly, a `status' statement value of
      `deprecated' may be revised as `obsolete'. When making such a
      change, the `description' statement SHOULD be updated to explain
      the rationale. 

   o  In `typedef', `scalar' and `column' statement blocks, a `default'
      statement may be added or updated. 



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   o  In any statement block, a `reference' statement may be added or
      updated. 

   o  In `typedef', `scalar' and `column' statement blocks, a `units'
      statement may be added. 

   o  A row may be augmented by adding new columnar objects (`column'
      statements) at the end of the row's statement block. 

   o  In any statement block, clarifications and additional information
      may be included in the `description' statement. 

   o  Entirely new extensions, types, nodes, scalar objects, tables,
      groups, or compliance statements may be defined, using previously
      unassigned identifiers and object identifier values. 

   Otherwise, if the semantics of any previous definition are changed
   (i.e., if a non-editorial change is made to any definition other
   than those specifically allowed above), then the `oid' statement
   value associated with that object MUST also be changed. 

   Note that changing the identifier associated with an existing object
   is considered a semantic change, as these strings may be used in an
   `import' statement. 



























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16. SMIng Language Extensibility

   While SMIng has a well defined set of statements (Section 5 through
   Section 13) that are used to specify those aspects of management
   information commonly regarded as necessary, there may be further
   information, people wish to express. To describe additional
   information informally in description statements has the
   disadvantage, that this information cannot be parsed by any program. 

   SMIng allows modules to include statements that are unknown to a
   parser but fulfill some core grammar rules (Section 4.2).
   Furthermore, additional statements may be defined by the `extension'
   statement (Section 6). Extensions can be used in the local module or
   in other modules, that import the extension. This has some
   advantages: 

   o  A parser can differentiate between statements known as extensions
      and unknown statements. This enables the parser to complain about
      unknown statements, e.g. due to typos. 

   o  If an extension's definition contains a formal ABNF grammar
      definition and a parser is able to interpret this ABNF
      definition, this enables the parser also to complain about wrong
      usage of an extension. 

   o  Since, there might be some common need for extensions, there is a
      relatively high probability of extension name collisions
      originated by different organizations, as long as there is no
      standardized extension for that purpose. The requirement to
      explicitly import extension statements allows to distinguish
      those extensions. 

   o  The supported extensions of an SMIng implementation, e.g. a MIB
      compiler, can be clearly expressed. 

   The only formal effect of an extension statement definition is to
   declare its existence and its status, and optionally its ABNF
   grammar. All additional aspects SHOULD be described in the
   `description' statement: 

   o  The detailed semantics of the new statement SHOULD be described. 

   o  The contexts in which the new statement can be used, SHOULD be
      described, e.g., a new statement may be designed to be used only
      in the statement block of a module, but not in other nested
      statement blocks. Others may be applicable in multiple contexts.
      In addition, the point in the sequence of an obligatory order of
      other statements, where the new statement may be inserted, might
      be prescribed. 


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   o  The circumstances that make the new statement mandatory or
      optional SHOULD be described. 

   o  The syntax of the new statement SHOULD at least be described
      informally, if not supplied formally in an `abnf' statement. 

   o  It might be reasonable to give some suggestions under which
      conditions the implementation of the new statement is adequate
      and how it could be integrated into existent implementations. 

   Some possible extension applications might be: 

   o  Agent capabilities statements, that allow to describe an agent
      implemention's deviation from the compliance statements of the
      modules they implement. SMIv2 has a regular AGENT-CAPABILITIES
      construct [4], though it's rarely used. That's why it's not a
      common SMIng statement. Instead, it is defined as an `agentcaps'
      extension statement in the module IRTF-NMRG-SMING-EXTENSIONS
      (Section 14.3). 

   o  Inlined annotations to definitions. E.g., a vendor may wish to
      describe additional information to object definitions in private
      modules. An example are severity levels of notifications in the
      statement block of a `notification' statement. 

   o  Arbitrary annotations to external definitions. E.g., a vendor may
      wish to describe additional information to object definitions in
      a "standard" module. This allows a vendor to implement "standard"
      modules as well as additional private features, without redundant
      MIB definitions, but on top of "standard" MIB definitions. 





















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17. Module Conversions

17.1 Converting SMIv2 to SMIng

   Conversions of SMIv2 modules to SMIng are feasible. The only SMIv2
   construct that cannot be mapped to an SMIng statement is the
   AGENT-CAPABILITIES macro. However, this can be mapped to the
   `agentcaps' extension. All other constructs and types are directly
   mappable without loss of information. 

   Detailed mapping information is subject to a future document. 

17.2 Converting SMIng to SMIv2

   SMIng is more liberal in some aspects to ensure a more consistent
   information model and a short grammar with less exceptions. This
   leads to a limited backwards convertability to SMIv2 of different
   kinds of identifiers, groups, type definition hierarchies, octet
   string length limitations, and object identifier values (those with
   a single sub-identifier). Some other information gets lost when
   being converted to SMIv2: some occurences of references, units,
   formats, default values, table indexing information, and table row
   creation information. 

   Detailed mapping information is subject to a future document. 

17.3 SMIv1

   Conversions between SMIv1 and SMIng are not covered by this
   document. Anyhow, conversions between SMIv1 and SMIv2 are subject to
   SMIv2 and partly described in [14]. Conversions between SMIv2 and
   SMIng are covered in the sections above. 

   In few words, conversion from SMIv1 to SMIng is not possible in some
   cases and without some additional information. Conversion from SMIng
   to SMIv1 is possible if 64 bit types and floating point data types
   are not used and if identifiers conform to the SMIv1 restrictions. 














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18. Security Considerations

   This document defines a language with which to write and read
   descriptions of management information.  The language itself has no
   security impact on the Internet. 














































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19. Acknowledgements

   This document is originated as a central part of a master's thesis
   at the Technical University of Braunschweig, under the guidance of
   Juergen Schoenwaelder. 

   Since SMIng represents a successor of SMIv2, a huge amount of
   paragraphs and phrases are taken from the SMIv2 specifications [2],
   [3], [4] written by Jeff Case, Keith McCloghrie, David Perkins,
   Marshall T. Rose, Juergen Schoenwaelder, and Steven L. Waldbusser. 

   Finally, Marshall T. Rose's work on an XML framework for RFC authors
   [15] made the writing of an Internet standards document much more
   feasible. 

   Thanks to these people and the authors of these documents. 



































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References

   [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", RFC 2119, BCP 14, March 1997.

   [2]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M., Waldbusser, S., "Structure of Management Information
        Version 2 (SMIv2)", RFC 2578, STD 58, April 1999.

   [3]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M., Waldbusser, S., "Textual Conventions for SMIv2", RFC 2579,
        STD 59, April 1999.

   [4]  McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose,
        M., Waldbusser, S., "Conformance Statements for SMIv2", RFC
        2580, STD 60, April 1999.

   [5]  Rose, M., McCloghrie, K., "Structure and Identification of
        Management Information for TCP/IP-based Internets", RFC 1155,
        STD 16, May 1990.

   [6]  Rose, M., McCloghrie, K., "Concise MIB Definitions", RFC 1212,
        STD 16, March 1991.

   [7]  Rose, M., "A Convention for Defining Traps for use with the
        SNMP", RFC 1215, March 1991.

   [8]  Crocker, D., Overell, P., "Augmented BNF for Syntax
        Specifications: ABNF", RFC 2234, November 1997.

   [9]  International Organization for Standardization, "Specification
        of Abstract Syntax Notation One (ASN.1)", International
        Standard 8824, December 1987.

   [10]  Harrington, D., Presuhn, R., Wijnen, B., "An Architecture for
         Describing SNMP Management Frameworks", RFC 2271, January 1999.

   [11]  Institute of Electrical and Electronics Engineers, "IEEE
         Standard for Binary Floating-Point Arithmetic", ANSI/IEEE
         Standard 754-1985, August 1985.

   [12]  Yergeau, F., "UTF-8, a transformation format of ISO 10646",
         RFC 2279, January 1998.

   [13]  Case, J., McCloghrie, K., Rose, M., Waldbusser, S.,
         "Management Information Base for Version 2 of the Simple
         Network Management Protocol (SNMPv2)", RFC 1907, January 1996.

   [14]  Wijnen, B., Levi, D., "V2ToV1 - Mapping SNMPv2 onto SNMPv1


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         within a bi-lingual SNMP agent", RFC 2089, January 1997.

   [15]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, June
         1999.

Author's Address

   Frank Strauss
   TU Braunschweig
   Bueltenweg 74/75
   38106 Braunschweig
   Germany

   Phone: +49 531 391-3266
   EMail: strauss@ibr.cs.tu-bs.de
   URI:   http://www.ibr.cs.tu-bs.de/



































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Appendix A. The SMIng ABNF grammar

    The SMIng grammar conforms to the Augmented Backus-Naur Form
   (ABNF)[8], with one exception: For readability, keywords are
   represented as quoted strings, although ABNF would declare these
   strings to be case-insensitive.  Anyhow, SMIng keyword are meant to
   be case-sensitive. 

   ;;
   ;; sming.abnf -- SMIng grammar in ABNF notation (RFC 2234).
   ;;
   ;; @(#) $Id: draft-irtf-nmrg-sming-02.txt 8676 2008-01-17 23:11:17Z ispringer $
   ;;
   ;; Copyright (C) The Internet Society (1999). All Rights Reserved.
   ;;

   smingFile               = optsep *(moduleStatement optsep)

   ;;
   ;; Statement rules.
   ;;

   moduleStatement         = moduleKeyword sep ucIdentifier optsep "{" stmtsep
                                 *(importStatement stmtsep)
                                 organizationStatement stmtsep
                                 contactStatement stmtsep
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                                 1*(revisionStatement stmtsep)
                                 *1(identityStatement stmtsep)
                                 *(extensionStatement stmtsep)
                                 *(typedefStatement stmtsep)
                                 *(anyObjectStatement stmtsep)
                                 *(notificationStatement stmtsep)
                                 *(groupStatement stmtsep)
                                 *(complianceStatement stmtsep)
                             "}" optsep ";"

   extensionStatement      = extensionKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                                 *1(abnfStatement stmtsep)
                             "}" optsep ";"

   typedefStatement        = typedefKeyword sep ucIdentifier optsep
                                 "{" stmtsep
                                 typedefTypeStatement stmtsep


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                                 *1(defaultStatement stmtsep)
                                 *1(formatStatement stmtsep)
                                 *1(unitsStatement stmtsep)
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   anyObjectStatement      = nodeStatement /
                             scalarStatement /
                             tableStatement

   nodeStatement           = nodeKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 *1(statusStatement stmtsep)
                                 *1(descriptionStatement stmtsep)
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   scalarStatement         = scalarKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 typeStatement stmtsep
                                 accessStatement stmtsep
                                 *1(defaultStatement stmtsep)
                                 *1(formatStatement stmtsep)
                                 *1(unitsStatement stmtsep)
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   tableStatement          = tableKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                                 rowStatement stmtsep
                             "}" optsep ";"

   rowStatement            = rowKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 anyIndexStatement stmtsep
                                 *1(createStatement stmtsep)
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep


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                                 *1(referenceStatement stmtsep)
                                 1*(columnStatement stmtsep)
                             "}" optsep ";"

   columnStatement         = columnKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 typeStatement stmtsep
                                 accessStatement stmtsep
                                 *1(defaultStatement stmtsep)
                                 *1(formatStatement stmtsep)
                                 *1(unitsStatement stmtsep)
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   notificationStatement   = notificationKeyword sep lcIdentifier
                                 optsep "{" stmtsep
                                 oidStatement stmtsep
                                 *1(objectsStatement stmtsep)
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   groupStatement          = groupKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 membersStatement stmtsep
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                             "}" optsep ";"

   complianceStatement     = complianceKeyword sep lcIdentifier optsep
                                 "{" stmtsep
                                 oidStatement stmtsep
                                 *1(statusStatement stmtsep)
                                 descriptionStatement stmtsep
                                 *1(referenceStatement stmtsep)
                                 *1(mandatoryStatement stmtsep)
                                 *(optionalStatement stmtsep)
                                 *(refineStatement stmtsep)
                             "}" optsep ";"

   importStatement         = importKeyword sep ucIdentifier optsep
                                 "(" optsep
                                 identifierList optsep


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                             ")" optsep ";"

   revisionStatement       = revisionKeyword optsep "{" stmtsep
                                 dateStatement stmtsep
                                 descriptionStatement stmtsep
                             "}" optsep ";"

   identityStatement       = identityKeyword sep lcIdentifier optsep ";"

   typedefTypeStatement    = typeKeyword sep refinedBaseType optsep ";"

   typeStatement           = typeKeyword sep
                                 (refinedBaseType / refinedType)
                                 optsep ";"

   writetypeStatement      = writetypeKeyword sep
                                 (refinedBaseType / refinedType)
                                 optsep ";"

   anyIndexStatement       = indexStatement /
                             augmentsStatement /
                             reordersStatement /
                             sparseStatement /
                             expandsStatement

   indexStatement          = indexKeyword *1(sep impliedKeyword) optsep
                                 "(" optsep qlcIdentifierList
                                 optsep ")" optsep ";"

   augmentsStatement       = augmentsKeyword sep qlcIdentifier
                                 optsep ";"

   reordersStatement       = reordersKeyword sep qlcIdentifier
                                 *1(sep impliedKeyword)
                                 optsep "(" optsep
                                 qlcIdentifierList optsep ")"
                                 optsep ";"

   sparseStatement         = sparseKeyword sep qlcIdentifier optsep ";"

   expandsStatement        = expandsKeyword sep qlcIdentifier
                                 *1(sep impliedKeyword)
                                 optsep "(" optsep
                                 qlcIdentifierList optsep ")"
                                 optsep ";"

   createStatement         = createKeyword optsep ";"

   oidStatement            = oidKeyword sep objectIdentifier optsep ";"


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   dateStatement           = dateKeyword sep date optsep ";"

   organizationStatement   = organizationKeyword sep text optsep ";"

   contactStatement        = contactKeyword sep text optsep ";"

   formatStatement         = formatKeyword sep format optsep ";"

   unitsStatement          = unitsKeyword sep units optsep ";"

   statusStatement         = statusKeyword sep status optsep ";"

   accessStatement         = accessKeyword sep access optsep ";"

   defaultStatement        = defaultKeyword sep anyValue optsep ";"

   descriptionStatement    = descriptionKeyword sep text optsep ";"

   referenceStatement      = referenceKeyword sep text optsep ";"

   abnfStatement           = abnfKeyword sep text optsep ";"

   membersStatement        = membersKeyword optsep "(" optsep
                                 qlcIdentifierList optsep
                                 ")" optsep ";"

   objectsStatement        = objectsKeyword optsep "(" optsep
                                 qlcIdentifierList optsep
                                 ")" optsep ";"

   mandatoryStatement      = mandatoryKeyword optsep "(" optsep
                                 qlcIdentifierList optsep
                                 ")" optsep ";"

   optionalStatement       = optionalKeyword sep qlcIdentifier optsep
                                 "{" descriptionStatement stmtsep
                             "}" optsep ";"

   refineStatement         = refineKeyword sep qlcIdentifier optsep "{"
                                 *1(typeStatement stmtsep)
                                 *1(writetypeStatement stmtsep)
                                 *1(accessStatement stmtsep)
                                 descriptionStatement stmtsep
                             "}" optsep ";"

   ;;
   ;;
   ;;



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   refinedBaseType         = OctetStringKeyword *1(optsep numberSpec) /
                             ObjectIdentifierKeyword /
                             Integer32Keyword *1(optsep numberSpec) /
                             Unsigned32Keyword *1(optsep numberSpec) /
                             Integer64Keyword *1(optsep numberSpec) /
                             Unsigned64Keyword *1(optsep numberSpec) /
                             Float32Keyword *1(optsep floatSpec) /
                             Float64Keyword *1(optsep floatSpec) /
                             Float128Keyword *1(optsep floatSpec) /
                             EnumerationKeyword optsep namedNumberSpec /
   // TODO: inserted optsep, do also in parser grammar!
                             BitsKeyword optsep namedNumberSpec
   // TODO: inserted optsep, do also in parser grammar!

   refinedType             = qucIdentifier *1(optsep anySpec)

   anySpec                 = numberSpec / floatSpec

   numberSpec              = "(" optsep numberElement
                                 *furtherNumberElement
                                 optsep ")"

   furtherNumberElement    = optsep "|" optsep numberElement

   numberElement           = signedNumber *1numberUpperLimit

   numberUpperLimit        = optsep ".." optsep signedNumber

   floatSpec               = "(" optsep floatElement
                                 *furtherFloatElement
                                 optsep ")"

   furtherFloatElement     = optsep "|" optsep floatElement

   floatElement            = floatValue *1floatUpperLimit

   floatUpperLimit         = optsep ".." optsep floatValue

   namedNumberSpec         = "(" optsep namedNumberList optsep ")"

   namedNumberList         = namedNumberItem
                                 *(optsep "," optsep namedNumberItem)
                                 *1(optsep ",")

   namedNumberItem         = lcIdentifier optsep "(" optsep number
                                 optsep ")"

   identifierList          = identifier
                                 *(optsep "," optsep identifier)


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                                 *1(optsep ",")

   qIdentifierList         = qIdentifier
                                 *(optsep "," optsep qIdentifier)
                                 *1(optsep ",")

   qlcIdentifierList       = qlcIdentifier
                                 *(optsep "," optsep qlcIdentifier)
                                 *1(optsep ",")

   bitsValue               = "(" optsep bitsList optsep ")"

   bitsList                = *1(lcIdentifier
                                 *(optsep "," optsep lcIdentifier))
                                 *1(optsep ",")

   ;;
   ;; Other basic rules.
   ;;

   identifier              = ucIdentifier / lcIdentifier

   qIdentifier             = qucIdentifier / qlcIdentifier

   ucIdentifier            = ucAlpha *63(ALPHA / DIGIT / "-")

   qucIdentifier           = *1(ucIdentifier "::") ucIdentifier

   lcIdentifier            = lcAlpha *63(ALPHA / DIGIT / "-")

   qlcIdentifier           = *1(ucIdentifier "::") lcIdentifier

   text                    = textSegment *(optsep textSegment)

   textSegment             = DQUOTE *textAtom DQUOTE

   textAtom                = textVChar / HTAB / SP / lineBreak

   date                    = DQUOTE 4DIGIT "-" 2DIGIT "-" 2DIGIT
                                 *1(" " 2DIGIT ":" 2DIGIT)
                                 DQUOTE
                             ; always in UTC

   format                  = textSegment

   units                   = textSegment

   anyValue                = bitsValue /
                             negativeNumber /


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                             hexadecimalNumber /
                             floatValue /
                             text /
                             objectIdentifier
                             ; Note: `objectIdentifer' includes the
                             ; syntax of enumeration labels and postive
                             ; numbers. They are not named literally to
                             ; avoid reduce/reduce conflicts when
                             ; building LR parsers based on this
                             ; grammar.

   status                  = currentKeyword /
                             deprecatedKeyword /
                             obsoleteKeyword

   access                  = noaccessKeyword /
                             notifyonlyKeyword /
                             readonlyKeyword /
                             readwriteKeyword

   objectIdentifier        = (qlcIdentifier / subid) *127("." subid)

   subid                   = decimalNumber

   number                  = hexadecimalNumber / decimalNumber

   negativeNumber          = "-" decimalNumber

   signedNumber            = number / negativeNumber

   decimalNumber           = "0" / (nonZeroDigit *DIGIT)

   zeroDecimalNumber       = 1*DIGIT

   hexadecimalNumber       = "0x" 1*(HEXDIG HEXDIG)

   floatValue              = neginfKeyword /
                             posinfKeyword /
                             snanKeyword /
                             qnanKeyword /
                             signedNumber "." zeroDecimalNumber
                                 *1("E" ("+"/"-") zeroDecimalNumber)

   ;;
   ;; Rules to skip unknown statements
   ;; with arbitrary arguments and blocks.
   ;;

   unknownStatement        = unknownKeyword optsep *unknownArgument


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                                 optsep ";"

   unknownArgument         = ("(" optsep unknownList optsep ")") /
                             ("{" optsep *unknownStatement optsep "}") /
                             qucIdentifier /
                             anyValue /
                             anySpec

   unknownList             = namedNumberList /
                             qIdentifierList

   unknownKeyword          = lcIdentifier

   ;;
   ;; Keyword rules.
   ;;
   ;; Typically, keywords are represented by tokens returned from the
   ;; lexical analyzer.  Note, that the lexer has to be stateful to
   ;; distinguish keywords from identifiers depending on the context
   ;; position in the input stream.
   ;;
   ;; Also note, that these keyword definitions are represented in
   ;; cleartext for readability, while SMIng keywords are meant to be
   ;; case-sensitive, although ABNF makes quoted strings like these to
   ;; be case-insensitive.
   ;;

   ;; Statement keywords.

   moduleKeyword           = "module"
   importKeyword           = "import"
   revisionKeyword         = "revision"
   oidKeyword              = "oid"
   dateKeyword             = "date"
   organizationKeyword     = "organization"
   contactKeyword          = "contact"
   descriptionKeyword      = "description"
   referenceKeyword        = "reference"
   identityKeyword         = "identity"
   extensionKeyword        = "extension"
   typedefKeyword          = "typedef"
   typeKeyword             = "type"
   writetypeKeyword        = "writetype"
   nodeKeyword             = "node"
   scalarKeyword           = "scalar"
   tableKeyword            = "table"
   columnKeyword           = "column"
   rowKeyword              = "row"
   notificationKeyword     = "notification"


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   groupKeyword            = "group"
   complianceKeyword       = "compliance"
   formatKeyword           = "format"
   unitsKeyword            = "units"
   statusKeyword           = "status"
   accessKeyword           = "access"
   defaultKeyword          = "default"
   impliedKeyword          = "implied"
   indexKeyword            = "index"
   augmentsKeyword         = "augments"
   reordersKeyword         = "reorders"
   sparseKeyword           = "sparse"
   expandsKeyword          = "expands"
   createKeyword           = "create"
   membersKeyword          = "members"
   objectsKeyword          = "objects"
   mandatoryKeyword        = "mandatory"
   optionalKeyword         = "optional"
   refineKeyword           = "refine"
   abnfKeyword             = "abnf"

   ;; Base type keywords.

   OctetStringKeyword      = "OctetString"
   ObjectIdentifierKeyword = "ObjectIdentifier"
   Integer32Keyword        = "Integer32"
   Unsigned32Keyword       = "Unsigned32"
   Integer64Keyword        = "Integer64"
   Unsigned64Keyword       = "Unsigned64"
   Float32Keyword          = "Float32"
   Float64Keyword          = "Float64"
   Float128Keyword         = "Float128"
   BitsKeyword             = "Bits"
   EnumerationKeyword      = "Enumeration"

   ;; Status keyword.

   currentKeyword          = "current"
   deprecatedKeyword       = "deprecated"
   obsoleteKeyword         = "obsolete"

   ;; Access keywords.

   noaccessKeyword         = "noaccess"
   notifyonlyKeyword       = "notifyonly"
   readonlyKeyword         = "readonly"
   readwriteKeyword        = "readwrite"

   ;; Special floating point values' keywords.


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   neginfKeyword           = "neginf"
   posinfKeyword           = "posinf"
   snanKeyword             = "snan"
   qnanKeyword             = "qnan"

   ;;
   ;; Some low level rules.
   ;; These tokens are typically skipped by the lexical analyzer.
   ;;

   sep                     = 1*(comment / lineBreak / WSP)
                             ; unconditional separator

   optsep                  = *(comment / lineBreak / WSP)

   stmtsep                 = *(comment /
                               lineBreak /
                               WSP /
                               unknownStatement)

   comment                 = "//" *(WSP / VCHAR) lineBreak

   lineBreak               = CRLF / LF

   ;;
   ;; Encoding specific rules.
   ;;

   textVChar               = %x21 / %x23-7E
                             ; any VCHAR except DQUOTE

   ucAlpha                 = %x41-5A

   lcAlpha                 = %x61-7A

   nonZeroDigit            = %x31-39

   ;;
   ;; RFC 2234 core rules.
   ;;

   ALPHA          =  %x41-5A / %x61-7A
                          ; A-Z / a-z

   CR             =  %x0D
                          ; carriage return

   CRLF           =  CR LF
                          ; Internet standard newline


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   DIGIT          =  %x30-39
                          ; 0-9

   DQUOTE         =  %x22
                          ; " (Double Quote)

   HEXDIG         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"

   HTAB           =  %x09
                          ; horizontal tab

   LF             =  %x0A
                          ; linefeed

   SP             =  %x20
                          ; space

   VCHAR          =  %x21-7E
                          ; visible (printing) characters

   WSP            =  SP / HTAB
                          ; white space

   ;;
   ;; EOF
   ;;

























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Appendix B. Glossary

   columnar object: An object in a table row that may have zero, one or
      more object instances. Instances are identified by using the
      values of `indexing objects' as `instance identifier'. 

   extension: The SMIng `extension' statement can be used to define new
      statements. Extensions can express annotations to existent
      management information, agent capabilities known from SMIv2, or
      arbitrary other information. See Section 16 for details. 

   identifier: The name of any definition, either a module, type, node,
      scalar object, table, row, columnar object, notification, group,
      compliance, a named number of an enumeration or bits type or any
      construct defined by an SMIng extension. Every identifier starts
      with an upper-case or lower-case character, followed by letters,
      digits and hyphens, but without consecutive or trailing hyphens.
      The length of an identifier MUST NOT exceed 64 characters. Note
      that SMIng keywords may be used as identifiers, though it's NOT
      RECOMMENDED. See also Section 2.1. 

   indexing objects: A Table may contain multiple instances of single
      columnar objects. That is, there may be multiple rows. The
      table's `indexing objects' are used to unambiguously distinguish
      the rows of a table. A special encoding of their values
      represents the columns' instance-identifier, and thus identifies
      the row. 

   instance-identifier: That part of an object identifier value, that
      is used to unambiguously identify an instance of an object. For
      scalar objects, the instance-identifier is `0'. For columnar
      objects, the instance-identifier is built from the values of the
      `indexing objects'. See also Section 2.4. 

   module: A module is the container of inter-related management
      information, either managed objects or other definitions like
      type definitions or annotations. A module has to conform the
      SMIng grammar and semantics described by this document. A module
      represents a namespace in which local definitions are available
      and external definitions have to be imported. 

   named number: Values of `Enumeration' types (Section 3.10) and
      single elements of `Bits' (Section 3.11) types are integer
      numbers, each associated with an identifers. Those
      number-identifier pairs are called `named numbers'. 

   object: A leaf definition in the object identifier tree, that
      represents a class of object instances. Objects are exactly those
      definitions declared by the SMIng keywords `scalar' or `column'. 


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   object identifier: Management information is organized in a tree of
      nodes. Each node is unambiguously identified by an `object
      identifier', that consists of a sequence of integer numbers
      (`sub-identifiers') which represent the path of nodes from the
      root to the addressed node in the tree. See also Section 2. 

   row: The kind of node used to group columnar objects of a table.
      Some significant information on table indexing and information
      used for row creation and deletion is associated with a table's
      row definition. 

   scalar object: An object that has zero or one object instance. 

   sub-identifier: A single component of an object identifier. There
      are at most 128 sub-identifiers in an object identifier value and
      each sub-identifier has a maximum value of 2^32-1 (4294967295). 

   table: The kind of node used to group management information that is
      organized in a sequence of rows. 
































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Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implmentation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph
   are included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
























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