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Network Working Group T. Howes
Request for Comments: 1488 University of Michigan
S. Kille
ISODE Consortium
W. Yeong
Performance Systems International
C. Robbins
NeXor Ltd.
July 1993
The X.500 String Representation of Standard Attribute Syntaxes
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet
community, and requests discussion and suggestions for improvements.
Please refer to the current edition of the "IAB Official Protocol
Standards" 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 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 1488 X.500 Syntax Encoding July 1993
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.
2.2. Case Ignore String
A string of type caseIgnoreStringSyntax is encoded as the string
value itself.
Howes, Kille, Yeong & Robbins [Page 2]
RFC 1488 X.500 Syntax Encoding July 1993
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> '