path: root/source4/ldap_server/devdocs/rfc2252.txt

Network Working Group                                            M. Wahl
Request for Comments: 2252                           Critical Angle Inc.
Category: Standards Track                                    A. Coulbeck
                                                              Isode Inc.
                                                                T. Howes
                                           Netscape Communications Corp.
                                                                S. Kille
                                                           Isode Limited
                                                           December 1997


              Lightweight Directory Access Protocol (v3):
                      Attribute Syntax Definitions

1. Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1997).  All Rights Reserved.

IESG Note

   This document describes a directory access protocol that provides
   both read and update access.  Update access requires secure
   authentication, but this document does not mandate implementation of
   any satisfactory authentication mechanisms.

   In accordance with RFC 2026, section 4.4.1, this specification is
   being approved by IESG as a Proposed Standard despite this
   limitation, for the following reasons:

   a. to encourage implementation and interoperability testing of
      these protocols (with or without update access) before they
      are deployed, and

   b. to encourage deployment and use of these protocols in read-only
      applications.  (e.g. applications where LDAPv3 is used as
      a query language for directories which are updated by some
      secure mechanism other than LDAP), and






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   c. to avoid delaying the advancement and deployment of other Internet
      standards-track protocols which require the ability to query, but
      not update, LDAPv3 directory servers.

   Readers are hereby warned that until mandatory authentication
   mechanisms are standardized, clients and servers written according to
   this specification which make use of update functionality are
   UNLIKELY TO INTEROPERATE, or MAY INTEROPERATE ONLY IF AUTHENTICATION
   IS REDUCED TO AN UNACCEPTABLY WEAK LEVEL.

   Implementors are hereby discouraged from deploying LDAPv3 clients or
   servers which implement the update functionality, until a Proposed
   Standard for mandatory authentication in LDAPv3 has been approved and
   published as an RFC.

2. Abstract

   The Lightweight Directory Access Protocol (LDAP) [1] requires that
   the contents of AttributeValue fields in protocol elements be octet
   strings.  This document defines a set of syntaxes for LDAPv3, and the
   rules by which attribute values of these syntaxes are represented as
   octet strings for transmission in the LDAP protocol.  The syntaxes
   defined in this document are referenced by this and other documents
   that define attribute types.  This document also defines the set of
   attribute types which LDAP servers should support.

3. Overview

   This document defines the framework for developing schemas for
   directories accessible via the Lightweight Directory Access Protocol.

   Schema is the collection of attribute type definitions, object class
   definitions and other information which a server uses to determine
   how to match a filter or attribute value assertion (in a compare
   operation) against the attributes of an entry, and whether to permit
   add and modify operations.

   Section 4 states the general requirements and notations for attribute
   types, object classes, syntax and matching rule definitions.

   Section 5 lists attributes, section 6 syntaxes and section 7 object
   classes.

   Additional documents define schemas for representing real-world
   objects as directory entries.






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4. General Issues

   This document describes encodings used in an Internet protocol.

   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 RFC 2119 [4].

   Attribute Type and Object Class definitions are written in a string
   representation of the AttributeTypeDescription and
   ObjectClassDescription data types defined in X.501(93) [3].
   Implementors are strongly advised to first read the description of
   how schema is represented in X.500 before reading the rest of this
   document.

4.1. Common Encoding Aspects

   For the purposes of defining the encoding rules for attribute
   syntaxes, the following BNF definitions will be used.  They are based
   on the BNF styles of RFC 822 [13].

    a     = "a" / "b" / "c" / "d" / "e" / "f" / "g" / "h" / "i" /
            "j" / "k" / "l" / "m" / "n" / "o" / "p" / "q" / "r" /
            "s" / "t" / "u" / "v" / "w" / "x" / "y" / "z" / "A" /
            "B" / "C" / "D" / "E" / "F" / "G" / "H" / "I" / "J" /
            "K" / "L" / "M" / "N" / "O" / "P" / "Q" / "R" / "S" /
            "T" / "U" / "V" / "W" / "X" / "Y" / "Z"

    d               = "0" / "1" / "2" / "3" / "4" /
                      "5" / "6" / "7" / "8" / "9"

    hex-digit       =  d / "a" / "b" / "c" / "d" / "e" / "f" /
                           "A" / "B" / "C" / "D" / "E" / "F"

    k               = a / d / "-" / ";"

    p               = a / d / """ / "(" / ")" / "+" / "," /
                      "-" / "." / "/" / ":" / "?" / " "

    letterstring    = 1*a

    numericstring   = 1*d

    anhstring       = 1*k

    keystring       = a [ anhstring ]

    printablestring = 1*p



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    space           = 1*" "

    whsp            = [ space ]

    utf8            = <any sequence of octets formed from the UTF-8 [9]
                       transformation of a character from ISO10646 [10]>

    dstring         = 1*utf8

    qdstring        = whsp "'" dstring "'" whsp

    qdstringlist    = [ qdstring *( qdstring ) ]

    qdstrings       = qdstring / ( whsp "(" qdstringlist ")" whsp )

   In the following BNF for the string representation of OBJECT
   IDENTIFIERs, descr is the syntactic representation of an object
   descriptor, which consists of letters and digits, starting with a
   letter.  An OBJECT IDENTIFIER in the numericoid format should not
   have leading zeroes (e.g. "0.9.3" is permitted but "0.09.3" should
   not be generated).

   When encoding 'oid' elements in a value, the descr encoding option
   SHOULD be used in preference to the numericoid. An object descriptor
   is a more readable alias for a number OBJECT IDENTIFIER, and these
   (where assigned and known by the implementation) SHOULD be used in
   preference to numeric oids to the greatest extent possible.  Examples
   of object descriptors in LDAP are attribute type, object class and
   matching rule names.

     oid             = descr / numericoid

     descr           = keystring

     numericoid      = numericstring *( "." numericstring )

     woid            = whsp oid whsp

     ; set of oids of either form
     oids            = woid / ( "(" oidlist ")" )

     oidlist         = woid *( "$" woid )

     ; object descriptors used as schema element names
     qdescrs         = qdescr / ( whsp "(" qdescrlist ")" whsp )

     qdescrlist      = [ qdescr *( qdescr ) ]




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     qdescr          = whsp "'" descr "'" whsp

4.2. Attribute Types

   The attribute types are described by sample values for the subschema
   "attributeTypes" attribute, which is written in the
   AttributeTypeDescription syntax.  While lines have been folded for
   readability, the values transferred in protocol would not contain
   newlines.

   The AttributeTypeDescription is encoded according to the following
   BNF, and the productions for oid, qdescrs and qdstring are given in
   section 4.1.  Implementors should note that future versions of this
   document may have expanded this BNF to include additional terms.
   Terms which begin with the characters "X-" are reserved for private
   experiments, and MUST be followed by a <qdstrings>.

      AttributeTypeDescription = "(" whsp
            numericoid whsp              ; AttributeType identifier
          [ "NAME" qdescrs ]             ; name used in AttributeType
          [ "DESC" qdstring ]            ; description
          [ "OBSOLETE" whsp ]
          [ "SUP" woid ]                 ; derived from this other
                                         ; AttributeType
          [ "EQUALITY" woid              ; Matching Rule name
          [ "ORDERING" woid              ; Matching Rule name
          [ "SUBSTR" woid ]              ; Matching Rule name
          [ "SYNTAX" whsp noidlen whsp ] ; see section 4.3
          [ "SINGLE-VALUE" whsp ]        ; default multi-valued
          [ "COLLECTIVE" whsp ]          ; default not collective
          [ "NO-USER-MODIFICATION" whsp ]; default user modifiable
          [ "USAGE" whsp AttributeUsage ]; default userApplications
          whsp ")"

      AttributeUsage =
          "userApplications"     /
          "directoryOperation"   /
          "distributedOperation" / ; DSA-shared
          "dSAOperation"          ; DSA-specific, value depends on server

   Servers are not required to provide the same or any text in the
   description part of the subschema values they maintain.  Servers
   SHOULD provide at least one of the "SUP" and "SYNTAX" fields for each
   AttributeTypeDescription.

   Servers MUST implement all the attribute types referenced in sections
   5.1, 5.2 and 5.3.




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   Servers MAY recognize additional names and attributes not listed in
   this document, and if they do so, MUST publish the definitions of the
   types in the attributeTypes attribute of their subschema entries.

   Schema developers MUST NOT create attribute definitions whose names
   conflict with attributes defined for use with LDAP in existing
   standards-track RFCs.

   An AttributeDescription can be used as the value in a NAME part of an
   AttributeTypeDescription.  Note that these are case insensitive.

   Note that the AttributeTypeDescription does not list the matching
   rules which can can be used with that attribute type in an
   extensibleMatch search filter.  This is done using the
   matchingRuleUse attribute described in section 4.5.

   This document refines the schema description of X.501 by requiring
   that the syntax field in an AttributeTypeDescription be a string
   representation of an OBJECT IDENTIFIER for the LDAP string syntax
   definition, and an optional indication of the maximum length of a
   value of this attribute (defined in section 4.3.2).

4.3. Syntaxes

   This section defines general requirements for LDAP attribute value
   syntax encodings. All documents defining attribute syntax encodings
   for use with LDAP are expected to conform to these requirements.

   The encoding rules defined for a given attribute syntax must produce
   octet strings.  To the greatest extent possible, encoded octet
   strings should be usable in their native encoded form for display
   purposes. In particular, encoding rules for attribute syntaxes
   defining non-binary values should produce strings that can be
   displayed with little or no translation by clients implementing LDAP.
   There are a few cases (e.g. audio) however, when it is not sensible
   to produce a printable representation, and clients MUST NOT assume
   that an unrecognized syntax is a string representation.

   In encodings where an arbitrary string, not a Distinguished Name, is
   used as part of a larger production, and other than as part of a
   Distinguished Name, a backslash quoting mechanism is used to escape
   the following separator symbol character (such as "'", "$" or "#") if
   it should occur in that string.  The backslash is followed by a pair
   of hexadecimal digits representing the next character.  A backslash
   itself in the string which forms part of a larger syntax is always
   transmitted as '\5C' or '\5c'. An example is given in section 6.27.





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   Syntaxes are also defined for matching rules whose assertion value
   syntax is different from the attribute value syntax.

4.3.1  Binary Transfer of Values

   This encoding format is used if the binary encoding is requested by
   the client for an attribute, or if the attribute syntax name is
   "1.3.6.1.4.1.1466.115.121.1.5".  The contents of the LDAP
   AttributeValue or AssertionValue field is a BER-encoded instance of
   the attribute value or a matching rule assertion value ASN.1 data
   type as defined for use with X.500. (The first byte inside the OCTET
   STRING wrapper is a tag octet.  However, the OCTET STRING is still
   encoded in primitive form.)

   All servers MUST implement this form for both generating attribute
   values in search responses, and parsing attribute values in add,
   compare and modify requests, if the attribute type is recognized and
   the attribute syntax name is that of Binary.  Clients which request
   that all attributes be returned from entries MUST be prepared to
   receive values in binary (e.g. userCertificate;binary), and SHOULD
   NOT simply display binary or unrecognized values to users.

4.3.2. Syntax Object Identifiers

   Syntaxes for use with LDAP are named by OBJECT IDENTIFIERs, which are
   dotted-decimal strings.  These are not intended to be displayed to
   users.

   noidlen = numericoid [ "{" len "}" ]

   len     = numericstring

   The following table lists some of the syntaxes that have been defined
   for LDAP thus far.  The H-R column suggests whether a value in that
   syntax would likely be a human readable string.  Clients and servers
   need not implement all the syntaxes listed here, and MAY implement
   other syntaxes.

   Other documents may define additional syntaxes.  However, the
   definition of additional arbitrary syntaxes is strongly deprecated
   since it will hinder interoperability: today's client and server
   implementations generally do not have the ability to dynamically
   recognize new syntaxes.  In most cases attributes will be defined
   with the syntax for directory strings.







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   Value being represented        H-R OBJECT IDENTIFIER
   =================================================================
   ACI Item                        N  1.3.6.1.4.1.1466.115.121.1.1
   Access Point                    Y  1.3.6.1.4.1.1466.115.121.1.2
   Attribute Type Description      Y  1.3.6.1.4.1.1466.115.121.1.3
   Audio                           N  1.3.6.1.4.1.1466.115.121.1.4
   Binary                          N  1.3.6.1.4.1.1466.115.121.1.5
   Bit String                      Y  1.3.6.1.4.1.1466.115.121.1.6
   Boolean                         Y  1.3.6.1.4.1.1466.115.121.1.7
   Certificate                     N  1.3.6.1.4.1.1466.115.121.1.8
   Certificate List                N  1.3.6.1.4.1.1466.115.121.1.9
   Certificate Pair                N  1.3.6.1.4.1.1466.115.121.1.10
   Country String                  Y  1.3.6.1.4.1.1466.115.121.1.11
   DN                              Y  1.3.6.1.4.1.1466.115.121.1.12
   Data Quality Syntax             Y  1.3.6.1.4.1.1466.115.121.1.13
   Delivery Method                 Y  1.3.6.1.4.1.1466.115.121.1.14
   Directory String                Y  1.3.6.1.4.1.1466.115.121.1.15
   DIT Content Rule Description    Y  1.3.6.1.4.1.1466.115.121.1.16
   DIT Structure Rule Description  Y  1.3.6.1.4.1.1466.115.121.1.17
   DL Submit Permission            Y  1.3.6.1.4.1.1466.115.121.1.18
   DSA Quality Syntax              Y  1.3.6.1.4.1.1466.115.121.1.19
   DSE Type                        Y  1.3.6.1.4.1.1466.115.121.1.20
   Enhanced Guide                  Y  1.3.6.1.4.1.1466.115.121.1.21
   Facsimile Telephone Number      Y  1.3.6.1.4.1.1466.115.121.1.22
   Fax                             N  1.3.6.1.4.1.1466.115.121.1.23
   Generalized Time                Y  1.3.6.1.4.1.1466.115.121.1.24
   Guide                           Y  1.3.6.1.4.1.1466.115.121.1.25
   IA5 String                      Y  1.3.6.1.4.1.1466.115.121.1.26
   INTEGER                         Y  1.3.6.1.4.1.1466.115.121.1.27
   JPEG                            N  1.3.6.1.4.1.1466.115.121.1.28
   LDAP Syntax Description         Y  1.3.6.1.4.1.1466.115.121.1.54
   LDAP Schema Definition          Y  1.3.6.1.4.1.1466.115.121.1.56
   LDAP Schema Description         Y  1.3.6.1.4.1.1466.115.121.1.57
   Master And Shadow Access Points Y  1.3.6.1.4.1.1466.115.121.1.29
   Matching Rule Description       Y  1.3.6.1.4.1.1466.115.121.1.30
   Matching Rule Use Description   Y  1.3.6.1.4.1.1466.115.121.1.31
   Mail Preference                 Y  1.3.6.1.4.1.1466.115.121.1.32
   MHS OR Address                  Y  1.3.6.1.4.1.1466.115.121.1.33
   Modify Rights                   Y  1.3.6.1.4.1.1466.115.121.1.55
   Name And Optional UID           Y  1.3.6.1.4.1.1466.115.121.1.34
   Name Form Description           Y  1.3.6.1.4.1.1466.115.121.1.35
   Numeric String                  Y  1.3.6.1.4.1.1466.115.121.1.36
   Object Class Description        Y  1.3.6.1.4.1.1466.115.121.1.37
   Octet String                    Y  1.3.6.1.4.1.1466.115.121.1.40
   OID                             Y  1.3.6.1.4.1.1466.115.121.1.38
   Other Mailbox                   Y  1.3.6.1.4.1.1466.115.121.1.39
   Postal Address                  Y  1.3.6.1.4.1.1466.115.121.1.41
   Protocol Information            Y  1.3.6.1.4.1.1466.115.121.1.42



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   Presentation Address            Y  1.3.6.1.4.1.1466.115.121.1.43
   Printable String                Y  1.3.6.1.4.1.1466.115.121.1.44
   Substring Assertion             Y  1.3.6.1.4.1.1466.115.121.1.58
   Subtree Specification           Y  1.3.6.1.4.1.1466.115.121.1.45
   Supplier Information            Y  1.3.6.1.4.1.1466.115.121.1.46
   Supplier Or Consumer            Y  1.3.6.1.4.1.1466.115.121.1.47
   Supplier And Consumer           Y  1.3.6.1.4.1.1466.115.121.1.48
   Supported Algorithm             N  1.3.6.1.4.1.1466.115.121.1.49
   Telephone Number                Y  1.3.6.1.4.1.1466.115.121.1.50
   Teletex Terminal Identifier     Y  1.3.6.1.4.1.1466.115.121.1.51
   Telex Number                    Y  1.3.6.1.4.1.1466.115.121.1.52
   UTC Time                        Y  1.3.6.1.4.1.1466.115.121.1.53

   A suggested minimum upper bound on the number of characters in value
   with a string-based syntax, or the number of bytes in a value for all
   other syntaxes, may be indicated by appending this bound count inside
   of curly braces following the syntax name's OBJECT IDENTIFIER in an
   Attribute Type Description.  This bound is not part of the syntax
   name itself.  For instance, "1.3.6.4.1.1466.0{64}" suggests that
   server implementations should allow a string to be 64 characters
   long, although they may allow longer strings.  Note that a single
   character of the Directory String syntax may be encoded in more than
   one byte since UTF-8 is a variable-length encoding.

4.3.3. Syntax Description

   The following BNF may be used to associate a short description with a
   syntax OBJECT IDENTIFIER. Implementors should note that future
   versions of this document may expand this definition to include
   additional terms.  Terms whose identifier begins with "X-" are
   reserved for private experiments, and MUST be followed by a
   <qdstrings>.

      SyntaxDescription = "(" whsp
          numericoid whsp
          [ "DESC" qdstring ]
          whsp ")"

4.4. Object Classes

   The format for representation of object classes is defined in X.501
   [3]. In general every entry will contain an abstract class ("top" or
   "alias"), at least one structural object class, and zero or more
   auxiliary object classes.  Whether an object class is abstract,
   structural or auxiliary is defined when the object class identifier
   is assigned.  An object class definition should not be changed
   without having a new identifier assigned to it.




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   Object class descriptions are written according to the following BNF.
   Implementors should note that future versions of this document may
   expand this definition to include additional terms.  Terms whose
   identifier begins with "X-" are reserved for private experiments, and
   MUST be followed by a <qdstrings> encoding.

      ObjectClassDescription = "(" whsp
          numericoid whsp      ; ObjectClass identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" whsp ]
          [ "SUP" oids ]       ; Superior ObjectClasses
          [ ( "ABSTRACT" / "STRUCTURAL" / "AUXILIARY" ) whsp ]
                               ; default structural
          [ "MUST" oids ]      ; AttributeTypes
          [ "MAY" oids ]       ; AttributeTypes
      whsp ")"

   These are described as sample values for the subschema
   "objectClasses" attribute for a server which implements the LDAP
   schema. While lines have been folded for readability, the values
   transferred in protocol would not contain newlines.

   Servers SHOULD implement all the object classes referenced in section
   7, except for extensibleObject, which is optional. Servers MAY
   implement additional object classes not listed in this document, and
   if they do so, MUST publish the definitions of the classes in the
   objectClasses attribute of their subschema entries.

   Schema developers MUST NOT create object class definitions whose
   names conflict with attributes defined for use with LDAP in existing
   standards-track RFCs.

4.5. Matching Rules

   Matching rules are used by servers to compare attribute values
   against assertion values when performing Search and Compare
   operations.  They are also used to identify the value to be added or
   deleted when modifying entries, and are used when comparing a
   purported distinguished name with the name of an entry.

   Most of the attributes given in this document will have an equality
   matching rule defined.

   Matching rule descriptions are written according to the following
   BNF.  Implementors should note that future versions of this document
   may have expanded this BNF to include additional terms.  Terms whose
   identifier begins with "X-" are reserved for private experiments, and



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   MUST be followed by a <qdstrings> encoding.

      MatchingRuleDescription = "(" whsp
          numericoid whsp  ; MatchingRule identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" whsp ]
          "SYNTAX" numericoid
      whsp ")"

   Values of the matchingRuleUse list the attributes which are suitable
   for use with an extensible matching rule.

      MatchingRuleUseDescription = "(" whsp
          numericoid whsp  ; MatchingRule identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" ]
         "APPLIES" oids    ; AttributeType identifiers
      whsp ")"

   Servers which support matching rules and the extensibleMatch SHOULD
   implement all the matching rules in section 8.

   Servers MAY implement additional matching rules not listed in this
   document, and if they do so, MUST publish the definitions of the
   matching rules in the matchingRules attribute of their subschema
   entries. If the server supports the extensibleMatch, then the server
   MUST publish the relationship between the matching rules and
   attributes in the matchingRuleUse attribute.

   For example, a server which implements a privately-defined matching
   rule for performing sound-alike matches on Directory String-valued
   attributes would include the following in the subschema entry
   (1.2.3.4.5 is an example, the OID of an actual matching rule would be
   different):

   matchingRule: ( 1.2.3.4.5 NAME 'soundAlikeMatch'
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )

   If this matching rule could be used with the attributes 2.5.4.41 and
   2.5.4.15, the following would also be present:

   matchingRuleUse: ( 1.2.3.4.5 APPLIES (2.5.4.41 $ 2.5.4.15) )







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   A client could then make use of this matching rule by sending a
   search operation in which the filter is of the extensibleMatch
   choice, the matchingRule field is "soundAlikeMatch", and the type
   field is "2.5.4.41" or "2.5.4.15".

5. Attribute Types

   All LDAP server implementations MUST recognize the attribute types
   defined in this section.

   Servers SHOULD also recognize all the attributes from section 5 of
   [12].

5.1. Standard Operational Attributes

   Servers MUST maintain values of these attributes in accordance with
   the definitions in X.501(93).

5.1.1. createTimestamp

   This attribute SHOULD appear in entries which were created using the
   Add operation.

    ( 2.5.18.1 NAME 'createTimestamp' EQUALITY generalizedTimeMatch
      ORDERING generalizedTimeOrderingMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
      SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation )

5.1.2. modifyTimestamp

   This attribute SHOULD appear in entries which have been modified
   using the Modify operation.

    ( 2.5.18.2 NAME 'modifyTimestamp' EQUALITY generalizedTimeMatch
      ORDERING generalizedTimeOrderingMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
      SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation )

5.1.3. creatorsName

   This attribute SHOULD appear in entries which were created using the
   Add operation.

    ( 2.5.18.3 NAME 'creatorsName' EQUALITY distinguishedNameMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
      SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation )





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5.1.4. modifiersName

   This attribute SHOULD appear in entries which have been modified
   using the Modify operation.

    ( 2.5.18.4 NAME 'modifiersName' EQUALITY distinguishedNameMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
      SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation )

5.1.5. subschemaSubentry

   The value of this attribute is the name of a subschema entry (or
   subentry if the server is based on X.500(93)) in which the server
   makes available attributes specifying the schema.

    ( 2.5.18.10 NAME 'subschemaSubentry'
      EQUALITY distinguishedNameMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.12 NO-USER-MODIFICATION
      SINGLE-VALUE USAGE directoryOperation )

5.1.6. attributeTypes

   This attribute is typically located in the subschema entry.

    ( 2.5.21.5 NAME 'attributeTypes'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.3 USAGE directoryOperation )

5.1.7. objectClasses

   This attribute is typically located in the subschema entry.

    ( 2.5.21.6 NAME 'objectClasses'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.37 USAGE directoryOperation )

5.1.8. matchingRules

   This attribute is typically located in the subschema entry.

    ( 2.5.21.4 NAME 'matchingRules'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.30 USAGE directoryOperation )








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5.1.9. matchingRuleUse

   This attribute is typically located in the subschema entry.

    ( 2.5.21.8 NAME 'matchingRuleUse'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.31 USAGE directoryOperation )

5.2. LDAP Operational Attributes

   These attributes are only present in the root DSE (see [1] and [3]).

   Servers MUST recognize these attribute names, but it is not required
   that a server provide values for these attributes, when the attribute
   corresponds to a feature which the server does not implement.

5.2.1. namingContexts

   The values of this attribute correspond to naming contexts which this
   server masters or shadows.  If the server does not master any
   information (e.g. it is an LDAP gateway to a public X.500 directory)
   this attribute will be absent.  If the server believes it contains
   the entire directory, the attribute will have a single value, and
   that value will be the empty string (indicating the null DN of the
   root). This attribute will allow a client to choose suitable base
   objects for searching when it has contacted a server.

    ( 1.3.6.1.4.1.1466.101.120.5 NAME 'namingContexts'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.12 USAGE dSAOperation )

5.2.2. altServer

   The values of this attribute are URLs of other servers which may be
   contacted when this server becomes unavailable.  If the server does
   not know of any other servers which could be used this attribute will
   be absent. Clients may cache this information in case their preferred
   LDAP server later becomes unavailable.

    ( 1.3.6.1.4.1.1466.101.120.6 NAME 'altServer'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 USAGE dSAOperation )

5.2.3. supportedExtension

   The values of this attribute are OBJECT IDENTIFIERs identifying the
   supported extended operations which the server supports.

   If the server does not support any extensions this attribute will be
   absent.



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    ( 1.3.6.1.4.1.1466.101.120.7 NAME 'supportedExtension'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 USAGE dSAOperation )

5.2.4. supportedControl

   The values of this attribute are the OBJECT IDENTIFIERs identifying
   controls which the server supports.  If the server does not support
   any controls, this attribute will be absent.

    ( 1.3.6.1.4.1.1466.101.120.13 NAME 'supportedControl'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 USAGE dSAOperation )

5.2.5. supportedSASLMechanisms

   The values of this attribute are the names of supported SASL
   mechanisms which the server supports.  If the server does not support
   any mechanisms this attribute will be absent.

    ( 1.3.6.1.4.1.1466.101.120.14 NAME 'supportedSASLMechanisms'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 USAGE dSAOperation )

5.2.6. supportedLDAPVersion

   The values of this attribute are the versions of the LDAP protocol
   which the server implements.

    ( 1.3.6.1.4.1.1466.101.120.15 NAME 'supportedLDAPVersion'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 USAGE dSAOperation )

5.3. LDAP Subschema Attribute

   This attribute is typically located in the subschema entry.

5.3.1. ldapSyntaxes

   Servers MAY use this attribute to list the syntaxes which are
   implemented.  Each value corresponds to one syntax.

    ( 1.3.6.1.4.1.1466.101.120.16 NAME 'ldapSyntaxes'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.54 USAGE directoryOperation )

5.4. X.500 Subschema attributes

   These attributes are located in the subschema entry.  All servers
   SHOULD recognize their name, although typically only X.500 servers
   will implement their functionality.




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5.4.1. dITStructureRules

 ( 2.5.21.1 NAME 'dITStructureRules' EQUALITY integerFirstComponentMatch
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.17 USAGE directoryOperation )

5.4.2. nameForms

    ( 2.5.21.7 NAME 'nameForms'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.35 USAGE directoryOperation )

5.4.3. ditContentRules

    ( 2.5.21.2 NAME 'dITContentRules'
      EQUALITY objectIdentifierFirstComponentMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.16 USAGE directoryOperation )

6. Syntaxes

   Servers SHOULD recognize all the syntaxes described in this section.

6.1. Attribute Type Description

   ( 1.3.6.1.4.1.1466.115.121.1.3 DESC 'Attribute Type Description' )

   Values in this syntax are encoded according to the BNF given at the
   start of section 4.2. For example,

        ( 2.5.4.0 NAME 'objectClass'
          SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 )

6.2. Binary

   ( 1.3.6.1.4.1.1466.115.121.1.5 DESC 'Binary' )

   Values in this syntax are encoded as described in section 4.3.1.

6.3. Bit String

   ( 1.3.6.1.4.1.1466.115.121.1.6 DESC 'Bit String' )

   Values in this syntax are encoded according to the following BNF:

      bitstring = "'" *binary-digit "'B"

      binary-digit = "0" / "1"





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   Example:

        '0101111101'B

6.4. Boolean

   ( 1.3.6.1.4.1.1466.115.121.1.7 DESC 'Boolean' )

   Values in this syntax are encoded according to the following BNF:

      boolean = "TRUE" / "FALSE"

   Boolean values have an encoding of "TRUE" if they are logically true,
   and have an encoding of "FALSE" otherwise.

6.5. Certificate

   ( 1.3.6.1.4.1.1466.115.121.1.8 DESC 'Certificate' )

   Because of the changes from X.509(1988) and X.509(1993) and
   additional changes to the ASN.1 definition to support certificate
   extensions, no string representation is defined, and values in this
   syntax MUST only be transferred using the binary encoding, by
   requesting or returning the attributes with descriptions
   "userCertificate;binary" or "caCertificate;binary".  The BNF notation
   in RFC 1778 for "User Certificate" is not recommended to be used.

6.6. Certificate List

   ( 1.3.6.1.4.1.1466.115.121.1.9 DESC 'Certificate List' )

   Because of the incompatibility of the X.509(1988) and X.509(1993)
   definitions of revocation lists, values in this syntax MUST only be
   transferred using a binary encoding, by requesting or returning the
   attributes with descriptions "certificateRevocationList;binary" or
   "authorityRevocationList;binary".  The BNF notation in RFC 1778 for
   "Authority Revocation List" is not recommended to be used.

6.7. Certificate Pair

   ( 1.3.6.1.4.1.1466.115.121.1.10 DESC 'Certificate Pair' )

   Because the Certificate is being carried in binary, values in this
   syntax MUST only be transferred using a binary encoding, by
   requesting or returning the attribute description
   "crossCertificatePair;binary". The BNF notation in RFC 1778 for
   "Certificate Pair" is not recommended to be used.




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6.8. Country String

   ( 1.3.6.1.4.1.1466.115.121.1.11 DESC 'Country String' )

   A value in this syntax is encoded the same as a value of Directory
   String syntax.  Note that this syntax is limited to values of exactly
   two printable string characters, as listed in ISO 3166 [14].

      CountryString  = p p

   Example:
      US

6.9. DN

   ( 1.3.6.1.4.1.1466.115.121.1.12 DESC 'DN' )

   Values in the Distinguished Name syntax are encoded to have the
   representation defined in [5].  Note that this representation is not
   reversible to an ASN.1 encoding used in X.500 for Distinguished
   Names, as the CHOICE of any DirectoryString element in an RDN is no
   longer known.

   Examples (from [5]):
      CN=Steve Kille,O=Isode Limited,C=GB
      OU=Sales+CN=J. Smith,O=Widget Inc.,C=US
      CN=L. Eagle,O=Sue\, Grabbit and Runn,C=GB
      CN=Before\0DAfter,O=Test,C=GB
      1.3.6.1.4.1.1466.0=#04024869,O=Test,C=GB
      SN=Lu\C4\8Di\C4\87

6.10. Directory String

   ( 1.3.6.1.4.1.1466.115.121.1.15 DESC 'Directory String' )

   A string in this syntax is encoded in the UTF-8 form of ISO 10646 (a
   superset of Unicode).  Servers and clients MUST be prepared to
   receive encodings of arbitrary Unicode characters, including
   characters not presently assigned to any character set.

   For characters in the PrintableString form, the value is encoded as
   the string value itself.

   If it is of the TeletexString form, then the characters are
   transliterated to their equivalents in UniversalString, and encoded
   in UTF-8 [9].





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   If it is of the UniversalString or BMPString forms [10], UTF-8 is
   used to encode them.

   Note: the form of DirectoryString is not indicated in protocol unless
   the attribute value is carried in binary.  Servers which convert to
   DAP MUST choose an appropriate form.  Servers MUST NOT reject values
   merely because they contain legal Unicode characters outside of the
   range of printable ASCII.

   Example:

      This is a string of DirectoryString containing #!%#@

6.11. DIT Content Rule Description

   ( 1.3.6.1.4.1.1466.115.121.1.16 DESC 'DIT Content Rule Description' )

   Values in this syntax are encoded according to the following BNF.
   Implementors should note that future versions of this document may
   have expanded this BNF to include additional terms.


      DITContentRuleDescription = "("
          numericoid   ; Structural ObjectClass identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" ]
          [ "AUX" oids ]    ; Auxiliary ObjectClasses
          [ "MUST" oids ]   ; AttributeType identifiers
          [ "MAY" oids ]    ; AttributeType identifiers
          [ "NOT" oids ]    ; AttributeType identifiers
         ")"

6.12. Facsimile Telephone Number


   ( 1.3.6.1.4.1.1466.115.121.1.22 DESC 'Facsimile Telephone Number' )

   Values in this syntax are encoded according to the following BNF:

      fax-number    = printablestring [ "$" faxparameters ]

      faxparameters = faxparm / ( faxparm "$" faxparameters )

      faxparm = "twoDimensional" / "fineResolution" /
                "unlimitedLength" /
                "b4Length" / "a3Width" / "b4Width" / "uncompressed"




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   In the above, the first printablestring is the telephone number,
   based on E.123 [15], and the faxparm tokens represent fax parameters.

6.13. Fax

   ( 1.3.6.1.4.1.1466.115.121.1.23 DESC 'Fax' )

   Values in this syntax are encoded as if they were octet strings
   containing Group 3 Fax images as defined in [7].

6.14. Generalized Time

   ( 1.3.6.1.4.1.1466.115.121.1.24 DESC 'Generalized Time' )

   Values in this syntax are encoded as printable strings, represented
   as specified in X.208.  Note that the time zone must be specified.
   It is strongly recommended that GMT time be used.  For example,

                199412161032Z

6.15. IA5 String

   ( 1.3.6.1.4.1.1466.115.121.1.26 DESC 'IA5 String' )

   The encoding of a value in this syntax is the string value itself.

6.16. INTEGER

   ( 1.3.6.1.4.1.1466.115.121.1.27 DESC 'INTEGER' )

   Values in this syntax are encoded as the decimal representation of
   their values, with each decimal digit represented by the its
   character equivalent. So the number 1321 is represented by the
   character string "1321".

6.17. JPEG

   ( 1.3.6.1.4.1.1466.115.121.1.28 DESC 'JPEG' )

   Values in this syntax are encoded as strings containing JPEG images
   in the JPEG File Interchange Format (JFIF), as described in [8].

6.18. Matching Rule Description

   ( 1.3.6.1.4.1.1466.115.121.1.30 DESC 'Matching Rule Description' )

   Values of type matchingRules are encoded as strings according to the
   BNF given in section 4.5.



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6.19. Matching Rule Use Description

   ( 1.3.6.1.4.1.1466.115.121.1.31 DESC 'Matching Rule Use Description'
   )

   Values of type matchingRuleUse are encoded as strings according to
   the BNF given in section 4.5.

6.20. MHS OR Address

   ( 1.3.6.1.4.1.1466.115.121.1.33 DESC 'MHS OR Address' )

   Values in this syntax are encoded as strings, according to the format
   defined in [11].

6.21. Name And Optional UID

   ( 1.3.6.1.4.1.1466.115.121.1.34 DESC 'Name And Optional UID' )

   Values in this syntax are encoded according to the following BNF:

      NameAndOptionalUID = DistinguishedName [ "#" bitstring ]

   Although the '#' character may occur in a string representation of a
   distinguished name, no additional special quoting is done.  This
   syntax has been added subsequent to RFC 1778.

   Example:

      1.3.6.1.4.1.1466.0=#04024869,O=Test,C=GB#'0101'B

6.22. Name Form Description

   ( 1.3.6.1.4.1.1466.115.121.1.35 DESC 'Name Form Description' )

   Values in this syntax are encoded according to the following BNF.
   Implementors should note that future versions of this document may
   have expanded this BNF to include additional terms.

      NameFormDescription = "(" whsp
          numericoid whsp  ; NameForm identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" whsp ]
          "OC" woid         ; Structural ObjectClass
          "MUST" oids       ; AttributeTypes
          [ "MAY" oids ]    ; AttributeTypes
      whsp ")"



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6.23. Numeric String

   ( 1.3.6.1.4.1.1466.115.121.1.36 DESC 'Numeric String' )

   The encoding of a string in this syntax is the string value itself.
   Example:

      1997

6.24. Object Class Description

   ( 1.3.6.1.4.1.1466.115.121.1.37 DESC 'Object Class Description' )

   Values in this syntax are encoded according to the BNF in section
   4.4.

6.25. OID

   ( 1.3.6.1.4.1.1466.115.121.1.38 DESC 'OID' )

   Values in the Object Identifier syntax are encoded according to
   the BNF in section 4.1 for "oid".

   Example:

      1.2.3.4
      cn

6.26. Other Mailbox

   ( 1.3.6.1.4.1.1466.115.121.1.39 DESC 'Other Mailbox' )

   Values in this syntax are encoded according to the following BNF:

      otherMailbox = mailbox-type "$" mailbox

      mailbox-type = printablestring

      mailbox = <an encoded IA5 String>

   In the above, mailbox-type represents the type of mail system in
   which the mailbox resides, for example "MCIMail"; and mailbox is the
   actual mailbox in the mail system defined by mailbox-type.

6.27. Postal Address

   ( 1.3.6.1.4.1.1466.115.121.1.41 DESC 'Postal Address' )




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   Values in this syntax are encoded according to the following BNF:

      postal-address = dstring *( "$" dstring )

   In the above, each dstring component of a postal address value is
   encoded as a value of type Directory String syntax.  Backslashes and
   dollar characters, if they occur in the component, are quoted as
   described in section 4.3.   Many servers limit the postal address to
   six lines of up to thirty characters.

   Example:

      1234 Main St.$Anytown, CA 12345$USA
      \241,000,000 Sweepstakes$PO Box 1000000$Anytown, CA 12345$USA

6.28. Presentation Address

   ( 1.3.6.1.4.1.1466.115.121.1.43 DESC 'Presentation Address' )

   Values in this syntax are encoded with the representation described
   in RFC 1278 [6].

6.29. Printable String

   ( 1.3.6.1.4.1.1466.115.121.1.44 DESC 'Printable String' )

   The encoding of a value in this syntax is the string value itself.
   PrintableString is limited to the characters in production p of
   section 4.1.

   Example:

      This is a PrintableString

6.30. Telephone Number

   ( 1.3.6.1.4.1.1466.115.121.1.50 DESC 'Telephone Number' )

   Values in this syntax are encoded as if they were Printable String
   types.  Telephone numbers are recommended in X.520 to be in
   international form, as described in E.123 [15].

   Example:

      +1 512 305 0280






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6.31. UTC Time

   ( 1.3.6.1.4.1.1466.115.121.1.53 DESC 'UTC Time' )

   Values in this syntax are encoded as if they were printable strings
   with the strings containing a UTCTime value.  This is historical; new
   attribute definitions SHOULD use GeneralizedTime instead.

6.32. LDAP Syntax Description

   ( 1.3.6.1.4.1.1466.115.121.1.54 DESC 'LDAP Syntax Description' )

   Values in this syntax are encoded according to the BNF in section
   4.3.3.

6.33. DIT Structure Rule Description

   ( 1.3.6.1.4.1.1466.115.121.1.17 DESC 'DIT Structure Rule Description'
   )

   Values with this syntax are encoded according to the following BNF:

      DITStructureRuleDescription = "(" whsp
          ruleidentifier whsp            ; DITStructureRule identifier
          [ "NAME" qdescrs ]
          [ "DESC" qdstring ]
          [ "OBSOLETE" whsp ]
          "FORM" woid whsp               ; NameForm
          [ "SUP" ruleidentifiers whsp ] ; superior DITStructureRules
      ")"

      ruleidentifier = integer

      ruleidentifiers = ruleidentifier |
          "(" whsp ruleidentifierlist whsp ")"

      ruleidentifierlist = [ ruleidentifier *( ruleidentifier ) ]

7. Object Classes

   Servers SHOULD recognize all the names of standard classes from
   section 7 of [12].

7.1. Extensible Object Class

   The extensibleObject object class, if present in an entry, permits
   that entry to optionally hold any attribute.  The MAY attribute list
   of this class is implicitly the set of all attributes.



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    ( 1.3.6.1.4.1.1466.101.120.111 NAME 'extensibleObject'
      SUP top AUXILIARY )

   The mandatory attributes of the other object classes of this entry
   are still required to be present.

   Note that not all servers will implement this object class, and those
   which do not will reject requests to add entries which contain this
   object class, or modify an entry to add this object class.

7.2. subschema

   This object class is used in the subschema entry.

    ( 2.5.20.1 NAME 'subschema' AUXILIARY
      MAY ( dITStructureRules $ nameForms $ ditContentRules $
      objectClasses $ attributeTypes $ matchingRules $
      matchingRuleUse ) )

   The ldapSyntaxes operational attribute may also be present in
   subschema entries.

8. Matching Rules

   Servers which implement the extensibleMatch filter SHOULD allow all
   the matching rules listed in this section to be used in the
   extensibleMatch.  In general these servers SHOULD allow matching
   rules to be used with all attribute types known to the server, when
   the assertion syntax of the matching rule is the same as the value
   syntax of the attribute.

   Servers MAY implement additional matching rules.

8.1. Matching Rules used in Equality Filters

   Servers SHOULD be capable of performing the following matching rules.

   For all these rules, the assertion syntax is the same as the value
   syntax.

    ( 2.5.13.0 NAME 'objectIdentifierMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 )

   If the client supplies a filter using an objectIdentifierMatch whose
   matchValue oid is in the "descr" form, and the oid is not recognized
   by the server, then the filter is Undefined.

    ( 2.5.13.1 NAME 'distinguishedNameMatch'



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      SYNTAX 1.3.6.1.4.1.1466.115.121.1.12 )

    ( 2.5.13.2 NAME 'caseIgnoreMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )

    ( 2.5.13.8 NAME 'numericStringMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.36 )

    ( 2.5.13.11 NAME 'caseIgnoreListMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.41 )

    ( 2.5.13.14 NAME 'integerMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )

    ( 2.5.13.16 NAME 'bitStringMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.6 )

    ( 2.5.13.20 NAME 'telephoneNumberMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.50 )

    ( 2.5.13.22 NAME 'presentationAddressMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.43 )

    ( 2.5.13.23 NAME 'uniqueMemberMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.34 )

    ( 2.5.13.24 NAME 'protocolInformationMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.42 )

    ( 2.5.13.27 NAME 'generalizedTimeMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )

    ( 1.3.6.1.4.1.1466.109.114.1 NAME 'caseExactIA5Match'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

    ( 1.3.6.1.4.1.1466.109.114.2 NAME 'caseIgnoreIA5Match'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

   When performing the caseIgnoreMatch, caseIgnoreListMatch,
   telephoneNumberMatch, caseExactIA5Match and caseIgnoreIA5Match,
   multiple adjoining whitespace characters are treated the same as an
   individual space, and leading and trailing whitespace is ignored.

   Clients MUST NOT assume that servers are capable of transliteration
   of Unicode values.






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8.2. Matching Rules used in Inequality Filters

   Servers SHOULD be capable of performing the following matching rules,
   which are used in greaterOrEqual and lessOrEqual filters.

    ( 2.5.13.28 NAME 'generalizedTimeOrderingMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )

    ( 2.5.13.3 NAME 'caseIgnoreOrderingMatch'
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 )

   The sort ordering for a caseIgnoreOrderingMatch is implementation-
   dependent.

8.3. Syntax and Matching Rules used in Substring Filters

   The Substring Assertion syntax is used only as the syntax of
   assertion values in the extensible match.  It is not used as the
   syntax of attributes, or in the substring filter.

   ( 1.3.6.1.4.1.1466.115.121.1.58 DESC 'Substring Assertion' )

   The Substring Assertion is encoded according to the following BNF:

      substring = [initial] any [final]
      initial = value
      any = "*" *(value "*")
      final = value

   The <value> production is UTF-8 encoded string.  Should the backslash
   or asterix characters be present in a production of <value>, they are
   quoted as described in section 4.3.

   Servers SHOULD be capable of performing the following matching rules,
   which are used in substring filters.

   ( 2.5.13.4 NAME 'caseIgnoreSubstringsMatch'
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.58 )

   ( 2.5.13.21 NAME 'telephoneNumberSubstringsMatch'
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.58 )

   ( 2.5.13.10 NAME 'numericStringSubstringsMatch'
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.58 )







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8.4. Matching Rules for Subschema Attributes

   Servers which allow subschema entries to be modified by clients MUST
   support the following matching rules, as they are the equality
   matching rules for several of the subschema attributes.

   ( 2.5.13.29 NAME 'integerFirstComponentMatch'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )

   ( 2.5.13.30 NAME 'objectIdentifierFirstComponentMatch'
     SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 )

   Implementors should note that the assertion syntax of these matching
   rules, an INTEGER or OID, is different from the value syntax of
   attributes for which this is the equality matching rule.

   If the client supplies an extensible filter using an
   objectIdentifierFirstComponentMatch whose matchValue is in the
   "descr" form, and the OID is not recognized by the server, then the
   filter is Undefined.

9. Security Considerations

9.1. Disclosure

   Attributes of directory entries are used to provide descriptive
   information about the real-world objects they represent, which can be
   people, organizations or devices.  Most countries have privacy laws
   regarding the publication of information about people.

9.2. Use of Attribute Values in Security Applications

   The transformations of an AttributeValue value from its X.501 form to
   an LDAP string representation are not always reversible back to the
   same BER or DER form.  An example of a situation which requires the
   DER form of a distinguished name is the verification of an X.509
   certificate.

   For example, a distinguished name consisting of one RDN with one AVA,
   in which the type is commonName and the value is of the TeletexString
   choice with the letters 'Sam' would be represented in LDAP as the
   string CN=Sam.  Another distinguished name in which the value is
   still 'Sam' but of the PrintableString choice would have the same
   representation CN=Sam.

   Applications which require the reconstruction of the DER form of the
   value SHOULD NOT use the string representation of attribute syntaxes
   when converting a value to LDAP format.  Instead it SHOULD use the



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   Binary syntax.

10. Acknowledgements

   This document is based substantially on RFC 1778, written by Tim
   Howes, Steve Kille, Wengyik Yeong and Colin Robbins.

   Many of the attribute syntax encodings defined in this and related
   documents are adapted from those used in the QUIPU and the IC R3
   X.500 implementations. The contributions of the authors of both these
   implementations in the specification of syntaxes are gratefully
   acknowledged.







































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11. Authors' Addresses

   Mark Wahl
   Critical Angle Inc.
   4815 West Braker Lane #502-385
   Austin, TX 78759
   USA

   Phone:  +1 512 372-3160
   EMail:  M.Wahl@critical-angle.com

   Andy Coulbeck
   Isode Inc.
   9390 Research Blvd Suite 305
   Austin, TX 78759
   USA

   Phone:  +1 512 231-8993
   EMail:  A.Coulbeck@isode.com

   Tim Howes
   Netscape Communications Corp.
   501 E. Middlefield Rd, MS MV068
   Mountain View, CA 94043
   USA

   Phone:  +1 650 937-3419
   EMail:   howes@netscape.com

   Steve Kille
   Isode Limited
   The Dome, The Square
   Richmond
   TW9 1DT
   UK

   Phone:  +44-181-332-9091
   EMail:  S.Kille@isode.com













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12. Bibliography

   [1] Wahl, M., Howes, T., and S. Kille, "Lightweight Directory Access
       Protocol (v3)", RFC 2251, December 1997.

   [2] The Directory: Selected Attribute Types.  ITU-T Recommendation
       X.520, 1993.

   [3] The Directory: Models. ITU-T Recommendation X.501, 1993.

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

   [5] Wahl, M., Kille, S., and T. Howes, "Lightweight Directory Access
       Protocol (v3): UTF-8 String Representation of
       Distinguished Names", RFC 2253, December 1997.

   [6] Kille, S., "A String Representation for Presentation Addresses",
       RFC 1278, November 1991.

   [7] Terminal Equipment and Protocols for Telematic Services -
       Standardization of Group 3 facsimile apparatus for document
       transmission.  CCITT, Recommendation T.4.

   [8] JPEG File Interchange Format (Version 1.02).  Eric Hamilton,
       C-Cube Microsystems, Milpitas, CA, September 1, 1992.

   [9] Yergeau, F., "UTF-8, a transformation format of Unicode and ISO
       10646", RFC 2044, October 1996.

   [10] Universal Multiple-Octet Coded Character Set (UCS) -
        Architecture and Basic Multilingual Plane, ISO/IEC 10646-1 :
        1993 (With amendments).

   [11] Hardcastle-Kille, S., "Mapping between X.400(1988) / ISO 10021
        and RFC 822", RFC 1327, May 1992.

   [12] Wahl, M., "A Summary of the X.500(96) User Schema for use
        with LDAPv3", RFC 2256, December 1997.

   [13] Crocker, D., "Standard of the Format of ARPA-Internet Text
        Messages", STD 11, RFC 822, August 1982.

   [14] ISO 3166, "Codes for the representation of names of countries".

   [15] ITU-T Rec. E.123, Notation for national and international
        telephone numbers, 1988.




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13.  Full Copyright Statement

   Copyright (C) The Internet Society (1997).  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 implementation 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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