Network Working Group T.
Request for Comments: 1488 University of
S.
ISODE
W.
Performance Systems
C.
NeXor Ltd
July 1993


The X.500 String Representation of Standard Attribute

Status of this

This RFC specifies an IAB standards track protocol for the
community, and requests discussion and suggestions for improvements
Please refer to the current edition of the "IAB Official
Standards" for the standardization state and status of this protocol
Distribution of this memo is unlimited



The Lightweight Directory Access Protocol (LDAP) [9] requires
the contents of AttributeValue fields in protocol elements be
strings. This document defines the requirements that must
satisfied by encoding rules used to render Directory
syntaxes into a form suitable for use in the LDAP, then goes on
define the encoding rules for the standard set of attribute
defined in [1,2] and [3].

1. Attribute Syntax Encoding

This section defines general requirements for lightweight
protocol attribute syntax encodings. All documents defining
syntax encodings for use by the lightweight directory protocols
expected to conform to these requirements

The encoding rules defined for a given attribute syntax must
octet strings. To the greatest extent possible, encoded
strings should be usable in their native encoded form for
purposes. In particular, encoding rules for attribute
defining non-binary values should produce strings that can
displayed with little or no translation by clients implementing
lightweight directory protocols






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RFC 1488 X.500 Syntax Encoding July 1993


2. Standard Attribute Syntax

For the purposes of defining the encoding rules for the
attribute syntaxes, the following auxiliary BNF definitions will
used

::= '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

::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'

::= | 'a' | 'b' | 'c' | 'd' | 'e' | 'f' |
'A' | 'B' | 'C' | 'D' | 'E' | 'F

::= | | '-'

::= | | ''' | '(' | ')' | '+' | ',' | '-' | '.' |
'/' | ':' | '?' | ' '

::= The ASCII newline character with hexadecimal value 0x0

::= |
::= |
::= |
::= |
<printablestring> ::=

|

<printablestring

::= ' ' | ' '
2.1.

Values of type Undefined are encoded as if they were values of
Octet String

2.2. Case Ignore

A string of type caseIgnoreStringSyntax is encoded as the
value itself





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2.3. Case Exact

The encoding of a string of type caseExactStringSyntax is the
value itself

2.4. Printable

The encoding of a string of type printableStringSyntax is the
value itself

2.5. Numeric

The encoding of a string of type numericStringSyntax is the
value itself

2.6. Octet

The encoding of a string of type octetStringSyntax is the
value itself

2.7. Case Ignore IA5

The encoding of a string of type caseIgnoreIA5String is the
value itself

2.8. IA5

The encoding of a string of type iA5StringSyntax is the string
itself

2.9. T61

The encoding of a string of type t61StringSyntax is the string
itself

2.10. Case Ignore

Values of type caseIgnoreListSyntax are encoded according to
following BNF

::= <caseignorestring> |
<caseignorestring> '$'
<caseignorestring> ::= a string encoded according to the
for Case Ignore String as above






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2.11. Case Exact

Values of type caseExactListSyntax are encoded according to
following BNF

::= |
'$'
::= a string encoded according to the rules
Case Exact String as above

2.12. Distinguished

Values of type distinguishedNameSyntax are encoded to have
representation defined in [5].

2.13.

Values of type booleanSyntax are encoded according to the
BNF

::= "TRUE" | "FALSE

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

2.14.

Values of type integerSyntax are encoded as the
representation of their values, with each decimal digit
by the its character equivalent. So the digit 1 is represented by


2.15. Object

Values of type objectIdentifierSyntax are encoded according to
following BNF

::= | '.' |
::=
::= | '.'
In the above BNF, is the syntactic representation of
object descriptor. When encoding values of
objectIdentifierSyntax, the first encoding option should be used
preference to the second, which should be used in preference to



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RFC 1488 X.500 Syntax Encoding July 1993


third wherever possible. That is, in encoding object identifiers
object descriptors (where assigned and known by the implementation
should be used in preference to numeric oids to the greatest
possible. For example, in encoding the object identifier
an organizationName, the descriptor "organizationName" is
to "ds.4.10", which is in turn preferable to the string "2.5.4.10".

2.16. Telephone

Values of type telephoneNumberSyntax are encoded as if they
Printable String types

2.17. Telex

Values of type telexNumberSyntax are encoded according to
following BNF

::= '$' '$' <answerback

::= <printablestring

::= <printablestring

<answerback> ::= <printablestring

In the above, is the syntactic representation of
number portion of the TELEX number being encoded, is
TELEX country code, and <answerback> is the answerback code of
TELEX terminal

2.18. Teletex Terminal

Values of type teletexTerminalIdentifier are encoded according to
following BNF

::= <printablestring> 0*( '$' <printablestring>)

In the above, the first <printablestring> is the encoding of
first portion of the teletex terminal identifier to be encoded,
the subsequent 0 or more are subsequent
of the teletex terminal identifier

2.19. Facsimile Telephone

Values of type FacsimileTelephoneNumber are encoded according to
following BNF

::= <printablestring> [ '$' ]



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RFC 1488 X.500 Syntax Encoding July 1993


::= | '$'
::= 'twoDimensional' | 'fineResolution' | 'unlimitedLength' |
'b4Length' | 'a3Width' | 'b4Width' | 'uncompressed

In the above, the first <printablestring> is the actual fax number
and the tokens represent fax parameters

2.20. Presentation

Values of type PresentationAddress are encoded to have
representation described in [6].

2.21. UTC

Values of type uTCTimeSyntax are encoded as if they were
Strings with the strings containing a UTCTime value

2.22. Guide (search guide

Values of type Guide, such as values of the searchGuide attribute
are encoded according to the following BNF

::= [ '#' ] <criteria

::= an encoded value of type

<criteria> ::= <criteria-item> | <criteria-set> | '!' <criteria

<criteria-set> ::= [ '(' ] <criteria> '&' <criteria-set> [ ')' ] |
[ '(' ] <criteria> '|' <criteria-set> [ ')' ]

<criteria-item> ::= [ '(' ] '$' [ ')' ]

::= "EQ" | "SUBSTR" | "GE" | "LE" | "APPROX

2.23. Postal

Values of type PostalAddress are encoded according to the following BNF

::= | '$'
In the above, each component of a postal address value
encoded as a value of type t61StringSyntax







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RFC 1488 X.500 Syntax Encoding July 1993


2.24. User

Values of type userPasswordSyntax are encoded as if they were of
octetStringSyntax

2.25. User

Values of type userCertificate are encoded according to the
BNF

<certificate> ::= <signature> '#' '#' <validity> '#' '#'
<signature> ::= <algorithm-id

::= an encoded Distinguished

<validity> ::= '#'
::=
::=
<algorithm-parameters> ::= | |
'{ASN}'
::= an encoded Distinguished

::= <algorithm-id> '#' <encrypted-value

<encrypted-value> ::= | '-'
<algorithm-id> ::= '#' <algorithm-parameters

::= an encoded UTCTime

::= |
2.26. CA

Values of type cACertificate are encoded as if the values were
type userCertificate

2.27. Authority Revocation

Values of type authorityRevocationList are encoded according to
following BNF




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RFC 1488 X.500 Syntax Encoding July 1993


<certificate-list> ::= <signature> '#' '#'
[ '#' ]

::= <algorithm> '#' <encrypted-value
[ '#' 0*(certificate>) '#']

::= '#' <algorithm> '#'
'#'
The syntactic components <algorithm>, , <encrypted-value>,
, and have the same definitions as
the BNF for the userCertificate attribute syntax

2.28. Certificate Revocation

Values of type certificateRevocationList are encoded as if the
were of type authorityRevocationList

2.29. Cross Certificate

Values of type crossCertificatePair are encoded according to
following BNF

<certificate-pair> ::= <certificate> '|' <certificate

The syntactic component <certificate> has the same definition as
the BNF for the userCertificate attribute syntax

2.30. Delivery

Values of type deliveryMethod are encoded according to the
BNF

<delivery-value> ::= | '$' <delivery-value

::= 'any' | 'mhs' | 'physical' | 'telex' | 'teletex' |
'g3fax' | 'g4fax' | 'ia5' | 'videotex' | 'telephone

2.31. Other

Values of the type otherMailboxSyntax are encoded according to
following BNF

::= '$'
::= an encoded Printable

::= an encoded IA5



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RFC 1488 X.500 Syntax Encoding July 1993


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

2.32. Mail

Values of type mailPreferenceOption are encoded according to
following BNF

preference> ::= "NO-LISTS" | "ANY-LIST" | "PROFESSIONAL-LISTS

2.33. MHS OR

Values of type MHS OR Address are encoded as strings, according
the format defined in [10].

2.34.

Values of type Photo are encoded as if they were octet
containing JPEG images in the JPEG File Interchange Format (JFIF),
described in [8].

2.35.

Values of type Fax are encoded as if they were octet
containing Group 3 Fax images as defined in [7].

3.

Many of the attribute syntax encodings defined in this document
adapted from those used in the QUIPU X.500 implementation.
contribu- tions of the authors of the QUIPU implementation in
specification of the QUIPU syntaxes [4] are gratefully acknowledged

4.

[1] The Directory: Selected Attribute Syntaxes. CCITT
Recommendation X.520.

[2] Information Processing Systems -- Open Systems Interconnection --
The Directory: Selected Attribute Syntaxes

[3] Barker, P., and S. Kille, "The COSINE and Internet X.500 Schema",
RFC 1274, University College London, November 1991.

[4] The ISO Development Environment: User's Manual -- Volume 5:
QUIPU. Colin Robbins, Stephen E. Kille



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RFC 1488 X.500 Syntax Encoding July 1993


[5] Kille, S., "A String Representation of Distinguished Names",
1485, July 1993.

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

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

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

[9] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory
Protocol", RFC 1487, Performance Systems International
University of Michigan, ISODE Consortium, July 1993.

[10] Kille, S., "Mapping between X.400(1988)/ISO 10021 and RFC 822",
RFC 1327, University College London, May 1992.

5. Security

Security issues are not discussed in this memo




























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RFC 1488 X.500 Syntax Encoding July 1993


6. Authors'

Tim
University of
ITD Research
535 W William St
Ann Arbor, MI 48103-4943


Phone: +1 313 747-4454
EMail: tim@umich.


Steve
ISODE
PO Box 505

SW11 1


Phone: +44-71-223-4062
EMail: S.Kille@isode.


Wengyik
PSI, Inc
510 Huntmar Park
Herndon, VA 22070


Phone: +1 703-450-8001
EMail: yeongw@psilink.


Colin
NeXor
University

NG7 2












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