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Network Working Group T. Howes
Request for Comments: 1778 University of Michigan
Obsoletes: 1488 S. Kille
Category: Standards Track ISODE Consortium
W. Yeong
Performance Systems International
C. Robbins
NeXor Ltd.
March 1995
The String Representation of Standard Attribute Syntaxes
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.
Abstract
The Lightweight Directory Access Protocol (LDAP) [9] requires that
the contents of AttributeValue fields in protocol elements be octet
strings. This document defines the requirements that must be
satisfied by encoding rules used to render X.500 Directory attribute
syntaxes into a form suitable for use in the LDAP, then goes on to
define the encoding rules for the standard set of attribute syntaxes
defined in [1,2] and [3].
1. Attribute Syntax Encoding Requirements.
This section defines general requirements for lightweight directory
protocol attribute syntax encodings. All documents defining attribute
syntax encodings for use by the lightweight directory protocols 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 the
lightweight directory protocols.
Howes, Kille, Yeong & Robbins [Page 1]
RFC 1778 Syntax Encoding March 1995
2. Standard Attribute Syntax Encodings
For the purposes of defining the encoding rules for the standard
attribute syntaxes, the following auxiliary BNF definitions will be
used:
<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> | ''' | '(' | ')' | '+' | ',' | '-' | '.' |
'/' | ':' | '?' | ' '
<CRLF> ::= The ASCII newline character with hexadecimal value 0x0A
<letterstring> ::= <a> | <a> <letterstring>
<numericstring> ::= <d> | <d> <numericstring>
<keystring> ::= <a> | <a> <anhstring>
<anhstring> ::= <k> | <k> <anhstring>
<printablestring> ::= <p> | <p> <printablestring>
<space> ::= ' ' | ' ' <space>
2.1. Undefined
Values of type Undefined are encoded as if they were values of type
Octet String, with the string value being the BER-encoded version of
the value.
2.2. Case Ignore String
A string of type caseIgnoreStringSyntax is encoded as the string
value itself.
Howes, Kille, Yeong & Robbins [Page 2]
RFC 1778 Syntax Encoding March 1995
2.3. Case Exact String
The encoding of a string of type caseExactStringSyntax is the string
value itself.
2.4. Printable String
The encoding of a string of type printableStringSyntax is the string
value itself.
2.5. Numeric String
The encoding of a string of type numericStringSyntax is the string
value itself.
2.6. Octet String
The encoding of a string of type octetStringSyntax is the string
value itself.
2.7. Case Ignore IA5 String
The encoding of a string of type caseIgnoreIA5String is the string
value itself.
2.8. IA5 String
The encoding of a string of type iA5StringSyntax is the string value
itself.
2.9. T61 String
The encoding of a string of type t61StringSyntax is the string value
itself.
2.10. Case Ignore List
Values of type caseIgnoreListSyntax are encoded according to the
following BNF:
<caseignorelist> ::= <caseignorestring> |
<caseignorestring> '