As per Relevance of the word represent, we have this rfc below:
Network Working Group S. Hardcastle-
Request for Comments: 1485 ISODE
July 1993
A String Representation of Distinguished
(OSI-DS 23 (v5))
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 OSI Directory uses distinguished names as the primary keys
entries in the directory. Distinguished Names are encoded in ASN.1.
When a distinguished name is communicated between to users not using
directory protocol (e.g., in a mail message), there is a need to
a user-oriented string representation of distinguished name.
specification defines a string format for representing names, which
designed to give a clean representation of commonly used names,
being able to represent any distinguished name. Please send
to the author or to the discussion group .
Table of
1. Why a notation is needed...................................... 1
2. A notation for Distinguished Name............................. 2
2.1 Goals......................................................... 2
2.2 Informal definition........................................... 2
2.3 Formal definition............................................. 3
3. Examples...................................................... 6
4. References.................................................... 6
5. Security Considerations....................................... 6
6. Author's Address.............................................. 7
1. Why a notation is
Many OSI Applications make use of Distinguished Names (DN) as
in the OSI Directory, commonly known as X.500 [CCI88].
specification assumes familiarity with X.500, and the concept
Distinguished Name. It is important to have a common format to
able to unambiguously represent a distinguished name. This might
done to represent a directory name on a business card or in an
Hardcastle-Kille [Page 1]
RFC 1485 Distinguished Names July 1993
message. There is a need for a format to support human to
communication, which must be string based (not ASN.1) and
oriented. This notation is targeted towards a general user
system, and in particular to represent the names of humans.
syntaxes may be more appropriate for other uses of the directory
For example, the OSF Syntax may be more appropriate for some
oriented uses. (The OSF Syntax uses "/" as a separator, and
names in a manner intended to resemble UNIX filenames).
2. A notation for Distinguished
2.1
The following goals are laid out
o To provide an unambiguous representation of a
o To be an intuitive format for the majority of
o To be fully general, and able to represent any
o To be amenable to a number of different layouts to achieve
attractive representation
o To give a clear representation of the contents of
distinguished
2.2 Informal
This notation is designed to be convenient for common forms of name
Some examples are given. The author's directory distinguished
would be written
CN=Steve Hardcastle-Kille, OU=Computer Science, O=
College London, C=
This may be folded, perhaps to display in multi-column format.
example
CN=Steve Hardcastle-Kille
OU=Computer Science
O=University College London
C=
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RFC 1485 Distinguished Names July 1993
Another name might be
CN=Christian Huitema, O=INRIA, C=
Semicolon (";") may be used as an alternate separator
CN=Christian Huitema; O=INRIA; C=
In running text, this would be written as
O=INRIA; C=FR>. Another example, shows how different attribute
are handled
CN=James Hacker
L=Basingstoke
O=Widget Inc
CN=
Here is an example of a multi-valued Relative Distinguished Name
where the namespace is flat within an organisation, and department
used to disambiguate certain names
OU=Sales + CN=J. Smith, O=Widget Inc., C=
The final example shows quoting of a comma in an Organisation name
CN=L. Eagle, O="Sue, Grabbit and Runn", C=
2.3 Formal
A formal definition can now be given. The structure is specified
a BNF grammar in Figure 1. This BNF uses the grammar defined in
822, with the terminals enclosed in <> [Cro82]. This definition
in an abstract character set, and so may be written in any
set supporting the explicitly defined special characters.
quoting mechanism is used for the following cases
o Strings containing ",", "+", "="or """, , "<",
">", "#", or ";".
o Strings with leading or trailing
o Strings containing consecutive
There is an escape mechanism from the normal user oriented form,
that this syntax may be used to print any valid distinguished name
This is ugly. It is expected to be used only in pathological cases
There are two parts to this mechanism
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RFC 1485 Distinguished Names July 1993
1. Attributes types are represented in a (big-endian)
notation. (e.g., OID.2.6.53).
2. Attribute values are represented in
(e.g., #0A56CF).
The keyword specification is optional in the BNF, but mandatory
this specification. This is so that the same BNF may be used for
related specification on User Friendly Naming [HK93]. When
specification is followed, the attribute type keywords must always
present. A list of valid keywords for well known attribute
used in naming is given in Table 1. This is a list of keywords
must be supported. These are chosen because they appear in
forms of name, and can do so in a place which does not correspond
the default schema used. A register of valid keyworkds is
by the IANA
Only string type attributes are considered, but other
syntaxes could be supported locally. It is assumed that
interface will translate from the supplied string
PrintableString or T.61.
The "+" notation is used to specify multi-component RDNs. In
case, the types for attributes in the RDN must be explicit. The
is presented/input in a little-endian order (most
component last).
When an address is written in a context where there is a need
delimit the entire address (e.g., in free text), it is
that the delimiters <> are used. The terminator > is a special
the notation to facilitate this delimitation
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RFC 1485 Distinguished Names July 1993
::= component> ( )
| component>
::= <optional-space
<optional-space
::= "," | ";"
<optional-space> ::= ( ) *( " " )
component> ::= <attribute
| <attribute> <optional-space> "+"
<optional-space> component
<attribute> ::=
| <optional-space> "=" <optional-space>
::= 1*( ) | "OID."
::= letters, numbers, and
::= | "."
::= 1*
::= digits 0-9
::= *( | )
| '"' *( | | ) '"'
| "#"
::= "," | "=" | '"' | | "+" | "<" | ">"
| "#" | ";"
::= "
::= any char except or "
::= 2*
::= 0-9, a-f, A-
Figure 1: BNF Grammar for Distinguished
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RFC 1485 Distinguished Names July 1993
Key Attribute (X.520 keys
______________________________
CN
L
ST
O
OU
C
Table 1: Standardised
3.
This section gives a few examples of distinguished names
using this notation
CN=Marshall T. Rose, O=Dover Beach Consulting, L=Santa Clara
ST=California, C=
CN=FTAM Service, CN=Bells, OU=Computer Science, O=
College London, C=
CN=Steve Hardcastle-Kille, OU=Computer Science, O=
College London, C=
CN=Steve Hardcastle-Kille, OU=Computer Science, O=
College London, C=
4.
[CCI88] The Directory --- overview of concepts, models and services
December 1988. CCITT X.500 Series Recommendations
[Cro82] D.H. Crocker. Standard of the format of ARPA internet
messages. STD 11, RFC 822, University of Delaware
August 1982.
[HK93] S.E. Hardcastle-Kille. Using the OSI directory to
user friendly naming. RFC 1484, Department of
Science, University College London, July 1993.
5. Security
Security issues are not discussed in this memo
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RFC 1485 Distinguished Names July 1993
6. Author's
Steve Hardcastle-
ISODE
P.O. Box 505
SW11 1
Phone:+44-71-223-4062
EMail: S.Kille@ISODE.
DN: CN=Steve Hardcastle-Kille
O=ISODE Consortium, C=
UFN: S. Hardcastle-Kille
ISODE Consortium,
Hardcastle-Kille [Page 7]
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