RFC 2294
Representing the O/R Address hierarchy in the X.500 Directory Information Tree
Representing the O/R Address hierarchy in the X.500 Directory Information Tree 💖
- RFC: 2294
- Network Working Group
- Authors: S. Kille, Isode Ltd.
- Date: March 1998
- Category: Standards Track
- Obsoletes: RFC 1836
- Updates: nothing listed in this header 🎀
Status of This Memo 🧾
Okay so this is an Internet standards track protocol 🌸 and it's literally asking the whole Internet community to talk about it and suggest improvements 💬. If you want the official status of this protocol, check the current edition of "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited ✨.
Copyright Notice 💜
Copyright (C) The Internet Society (1998). All Rights Reserved.
Abstract 🦋
So this doc defines a way to represent the O/R Address hierarchy in the Directory Information Tree [6, 1]. It's super useful for a few things, like:
- Support for MHS Routing [4].
- Support for X.400/RFC 822 address mappings [2, 5].
Send your comments to the author or to the discussion group <mhs-ds@mercury.udev.cdc.com> 💌
Object Class Mandatory
------------ ---------
mHSCountry M
aDMD M
pRMD O
mHSX121 O
mHSNumericUserIdentifier O
mHSOrganization O
mHSOrganizationalUnit O
mHSPerson O
mHSNamedObject O
mHSTerminalID O
mHSDomainDefinedAttribute OTable 1: Order of O/R Address Directory Components 📊
1. The O/R Address Hierarchy 🌈
Okay so an O/R Address hierarchy gets stored in the X.500 directory by matching up directory name components with O/R Address components, kind of like a bestie matchmaking 💘. Figure 1 shows an example, and the object classes and attributes needed to support this are in Figure 2. The schema that says how these objects get arranged in the directory information tree is in Table 1. Any object class higher up in the table will always sit higher in the DIT than one lower down 🧚. Valid combos of O/R Address components are defined in X.400 💅.
/\
/ \
C=GB / \ Numeric-C=234
/ \
/ \
/ \
+------------+<----------------+----+
| Country | | |
+------------+ +----+
/\
/ \
/ \
/ \
ADMD=" " / \ ADMD=Gold 400
+-------------+ +------------+
| ADMD | | ADMD |
+-------------+ +------------+
\ \
\ \
\ PRMD=UK.AC \ PRMD=UK.AC
\ \
+----------+ +----+
| PRMD |< -----------| |
+----------+ +----+
/
/
O=UCL
/
/
+------------+
| MHS-Org |
+------------+
\
\ OU=CS
\
\
+-----------+
| MHS-OU |
+-----------+Figure 1: Example O/R Address Tree 🌸
Here's the ASN.1 bit that brings it all together 🤓:
IMPORTS
ub-domain-name-length, ub-organization-name-length,
ub-organizational-unit-name-length, ub-common-name-length,
ub-x121-address-length, ub-domain-defined-attribute-type-length,
ub-domain-defined-attribute-value-length, ub-terminal-id-length,
ub-numeric-user-id-length, ub-country-name-numeric-length,
ub-surname-length, ub-given-name-length, ub-initials-length,
ub-generation-qualifier-length
FROM MTSUpperBounds {joint-iso-ccitt mhs-motis(6) mts(3) 10
modules(0) upper-bounds(3) };
mHSCountry OBJECT-CLASS ::= {
SUBCLASS OF {country}
MAY CONTAIN {mHSNumericCountryName}
ID oc-mhs-country}
mHSNumericCountryName ATTRIBUTE ::= {
WITH SYNTAX NumericString (SIZE (1..ub-country-name-numeric-length))
SINGLE VALUE 20
ID at-mhs-numeric-country-name}
aDMD OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {aDMDName}
ID oc-admd}
aDMDName ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-domain-name-length} 30
ID at-admd-name}
pRMD OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {pRMDName}
ID oc-prmd}
pRMDName ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-domain-name-length} 40
ID at-prmd-name}
mHSOrganization OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSOrganizationName }
ID oc-mhs-organization}
mHSOrganizationName ATTRIBUTE ::= {
SUBTYPE OF organizationName
WITH SYNTAX DirectoryString {ub-organization-name-length} 50
ID at-mhs-organization-name}
mHSOrganizationalUnit OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSOrganizationalUnitName}
ID oc-mhs-organizational-unit}
mHSOrganizationalUnitName ATTRIBUTE ::= {
SUBTYPE OF organizationalUnitName 60
WITH SYNTAX DirectoryString {ub-organizational-unit-name-length}
ID at-mhs-organizational-unit-name}
mHSPerson OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSSurname}
MAY CONTAIN {mHSGivenName|
mHSInitials|
mHSGenerationalQualifier}
ID oc-mhs-person} 70
mHSSurname ATTRIBUTE ::= {
SUBTYPE OF surname
WITH SYNTAX DirectoryString {ub-surname-length}
ID at-mhs-surname}
mHSGivenName ATTRIBUTE ::= {
SUBTYPE OF givenName
WITH SYNTAX DirectoryString {ub-given-name-length}
ID at-mhs-given-name} 80
mHSInitials ATTRIBUTE ::= {
SUBTYPE OF initials
WITH SYNTAX DirectoryString {ub-initials-length}
ID at-mhs-initials}
mHSGenerationQualifier ATTRIBUTE ::= {
SUBTYPE OF generationQualifier
WITH SYNTAX DirectoryString {ub-generation-qualifier-length}
ID at-mhs-generation-qualifier} 90
mHSNamedObject OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSCommonName}
ID oc-mhs-named-object}
mHSCommonName ATTRIBUTE ::= {
SUBTYPE OF commonName
WITH SYNTAX DirectoryString {ub-common-name-length}
ID at-mhs-common-name} 100
mHSX121 OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSX121Address}
ID oc-mhs-x121}
mHSX121Address ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-x121-address-length}
ID at-x121-address} 110
mHSDomainDefinedAttribute OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {
mHSDomainDefinedAttributeType|
mHSDomainDefinedAttributeValue}
ID oc-mhs-domain-defined-attribute}
mHSDomainDefinedAttributeType ATTRIBUTE ::= {
SUBTYPE OF name 120
WITH SYNTAX DirectoryString {ub-domain-defined-attribute-type-length}
SINGLE VALUE
ID at-mhs-domain-defined-attribute-type}
mHSDomainDefinedAttributeValue ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-domain-defined-attribute-value-length}
SINGLE VALUE
ID at-mhs-domain-defined-attribute-value}
130
mHSTerminalID OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSTerminalIDName}
ID oc-mhs-terminal-id}
mHSTerminalIDName ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-terminal-id-length}
ID at-mhs-terminal-id-name} 140
mHSNumericUserIdentifier OBJECT-CLASS ::= {
SUBCLASS OF {top}
MUST CONTAIN {mHSNumericUserIdentifierName}
ID oc-mhs-numeric-user-id}to be continued in part 2 🧚✨
mHSNumericeUserIdentifierName ATTRIBUTE ::= {
SUBTYPE OF name
WITH SYNTAX DirectoryString {ub-numeric-user-id-length} 150
ID at-mhs-numeric-user-id-name}Figure 2: O/R Address Hierarchy 🌸
Okay so here's the hierarchy, and it has some big rules, bestie 💅 Read these like they're the group chat rules:
- The representation is built so that a mechanical transformation in either direction is straightforward 🔄. That only works if every node is named by an attribute whose type can determine the mapping. It's giving reversible.
- Where there are multiple domain defined attributes, the first one in the sequence is the most significant 👑.
- Physical Delivery (postal) addresses are not represented in this hierarchy 📮. Mostly that's because physical delivery can be handled by the Access Unit routing mechanisms defined in [4], so there's no need for this representation.
- Terminal and network forms of address are not handled. The exception is the X.121 form, which is useful for addressing faxes 📠.
- MHSCountry is defined as a subclass of Country, so the same entry gets used for MHS Routing as for the rest of the DIT 🌍.
- The numeric country code will be an alias 🔢.
- ADMD will always be present in the hierarchy. This is true in the case of
" "and of"0". That makes it easy to transform mechanically between the two forms of address 🫶. - Each node is named by the relevant part of the O/R Address.
- Aliases may be used in other parts of the tree to normalize alternate values. Where an alias is used, the value of the alias should be present as an alternate value in the node aliased to. Aliases may not be used for domain defined attributes 🙅.
- Domain Defined Attributes are named by a multi-valued RDN (Relative Distinguished Name), made up of the type and value. This means standard attribute syntaxes can be used ✨.
- Where an O/R Address has a valid Printable String and T.61 form, both must be present, with one as an alias for the other. That way a direct lookup of the name works no matter which variant is used. When both are present in an O/R Address being looked up, either may be used to construct the distinguished name 🎀.
- Personal name is handled by the mHSPerson object class. Each component of the personal name will be present in the relative distinguished name, which will usually be multi-valued 🧑.
The relationship between X.400 O/R Addresses and the X.400 Entries (Attribute Type and Object Class) is given in Table 2. Where there are multiple Organizational Units or Domain Defined Attributes, each component is mapped onto a single X.500 entry 💖.
O/R Address Object Class Naming Attribute
----------- ------------ ----------------
C mHSCountry countryName
or
mHSNumericCountryName
A aDMD aDMDName
P pRMD pRMDName
O mHSOrganization mHSOrganizationName
OU/OU1/OU2 mHSOrganizationalUnit mHSOrganizationalUnitName
OU3/OU4
PN mHSPerson personName
CN mHSNamedObject mHSCommonName
X121 mHSX121 mHSX121Address
T-ID mHSTerminalID mHSTerminalIDName
UA-ID mHSNumericUserIdentifier mHSNumericUserIdentifierName
DDA mHSDomainDefinedAttribute mHSDomainDefinedAttributeType
and
mHSDomainDefinedAttributeValueTable 2: O/R Address relationship to Directory Name 🦋
Note: When an X.121 address is used for addressing fax transmission, this may only be done relative to the PRMD or ADMD. This is in line with the current X.400 standards position. This means that it is not possible to use this form of addressing for an organizational or departmental fax gateway service 📠💀.
2. Notation ✨
O/R Addresses are written in the standard X.400 Notation. Distinguished Names use the string representation of distinguished names defined in [3]. The keywords used for the attributes defined in this specification are given in Table 3 🌈.
3. Example Representation 🧚
Here's an example, so you can see it in action 👀. The O/R Address:
I=S; S=Kille; OU1=CS; O=UCL,
P=UK.AC; A=Gold 400; C=GB;would be represented in the directory as:
MHS-I=S + MHS-S=Kille, MHS-OU=CS, MHS-O=UCL, Attribute Keyword
--------- -------
mHSNumericCountryName MHS-Numeric-Country
aDMDName ADMD
pRMDName PRMD
mHSOrganizationName MHS-O
mHSOrganizationalUnitName MHS-OU
mHSSurname MHS-S
mHSGivenName MHS-G
mHSInitials MHS-I
mHSGenerationalQualifier MHS-GQ
mHSCommonName MHS-CN
mHSX121Address MHS-X121
mHSDomainDefinedAttributeType MHS-DDA-Type
mHSDomainDefinedAttributeValue MHS-DDA-Value
mHSTerminalIDName MHS-T-ID
mHSNumericeUserIdentifierName MHS-UA-IDTable 3: Keywords for String DN Representation 🍓
PRMD=UK.AC, ADMD=Gold 400, C=GB4. Mapping from O/R Address to Directory Name 🔥
The primary application of this mapping is to take an X.400 encoded O/R Address and generate an equivalent directory name. This mapping is only used for selected types of O/R Address:
- Mnemonic form
- Numeric form
- Terminal form, where country is present and X121 addressing is used
Other forms of O/R address are handled by Access Unit mechanisms. The O/R Address is treated as an ordered list, with the order as defined in Table 1 📋. For each O/R Address attribute, generate the equivalent directory naming attribute. In most cases, the mapping is mechanical. Printable String or Teletex encodings are chosen as appropriate. Where both forms are present in the O/R Address, either form may be used to generate the distinguished name. Both will be represented in the DIT. There are two special cases:
- A DDA generates a multi-valued RDN
- The Personal Name is mapped to a multi-valued RDN
In many cases, an O/R Address will be provided, and only the higher components of the address will be represented in the DIT. In this case, the "longest possible match" should be returned 🎯.
5. Mapping from Directory Name to O/R Address 🔁
The reverse mapping is also needed in some cases. All of the naming attributes are unique, so the mapping is mechanically reversible 💜.
6. Acknowledgments 🫶
Acknowledgments for work on this document are given in [4].
References 📚
[1] The Directory --- overview of concepts, models and services, 1993. CCITT X.500 Series Recommendations.
[2] Kille, S., "MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME", RFC 2156, January 1998.
[3] Kille, S., "A String Representation of Distinguished Names", RFC 1779, March 1995.
[4] Kille, S., "Use of an X.500/LDAP directory to support MIXER address mapping", RFC 2164, January 1998.
[5] Kille, S., "X.400-MHS use of the X.500 directory to support X.400-MHS routing", RFC 1801, June 1995.
[6] CCITT recommendations X.400 / ISO 10021, April 1988. CCITT SG 5/VII / ISO/IEC JTC1, Message Handling: System and Service Overview.
7. Security Considerations 🔒
This protocol introduces no known security risks. Stay safe out there, bestie 🫶.
8. Author's Address 🖋️
Steve Kille Isode Ltd. The Dome The Square Richmond TW9 1DT England
Phone: +44-181-332-9091 EMail: S.Kille@ISODE.COM
X.400: I=S; S=Kille; P=ISODE; A=Mailnet; C=FI;
A. Object Identifier Assignment 🧾
mhs-ds OBJECT IDENTIFIER ::= {iso(1) org(3) dod(6) internet(1) private(4)
enterprises(1) isode-consortium (453) mhs-ds (7)}
tree OBJECT IDENTIFIER ::= {mhs-ds 2}
oc OBJECT IDENTIFIER ::= {tree 1}
at OBJECT IDENTIFIER ::= {tree 2}
oc-admd OBJECT IDENTIFIER ::= {oc 1} 10
oc-mhs-country OBJECT IDENTIFIER ::= {oc 2}
oc-mhs-domain-defined-attribute OBJECT IDENTIFIER ::= {oc 3}
oc-mhs-named-object OBJECT IDENTIFIER ::= {oc 4}
oc-mhs-organization OBJECT IDENTIFIER ::= {oc 5}
oc-mhs-organizational-unit OBJECT IDENTIFIER ::= {oc 6}
oc-mhs-person OBJECT IDENTIFIER ::= {oc 7}
oc-mhs-x121 OBJECT IDENTIFIER ::= {oc 8}
oc-prmd OBJECT IDENTIFIER ::= {oc 9}
oc-mhs-terminal-id OBJECT IDENTIFIER ::= {oc 10}
oc-mhs-numeric-user-id OBJECT IDENTIFIER ::= {oc 11} 20
at-admd-name OBJECT IDENTIFIER ::= {at 1}
at-mhs-common-name OBJECT IDENTIFIER ::= {at 2}
at-mhs-domain-defined-attribute-type OBJECT IDENTIFIER ::= {at 3}
at-mhs-domain-defined-attribute-value OBJECT IDENTIFIER ::= {at 4}
at-mhs-numeric-country-name OBJECT IDENTIFIER ::= {at 5}
at-mhs-organization-name OBJECT IDENTIFIER ::= {at 6}
at-mhs-organizational-unit-name OBJECT IDENTIFIER ::= {at 7}
at-prmd-name OBJECT IDENTIFIER ::= {at 10}
at-x121-address OBJECT IDENTIFIER ::= {at 12} 30
at-mhs-terminal-id-name OBJECT IDENTIFIER ::= {at 13}
at-mhs-numeric-user-id-name OBJECT IDENTIFIER ::= {at 14}
at-mhs-surname OBJECT IDENTIFIER ::= {at 15}
at-mhs-given-name OBJECT IDENTIFIER ::= {at 16}
at-mhs-initials OBJECT IDENTIFIER ::= {at 17}
at-mhs-generation-qualifier OBJECT IDENTIFIER ::= {at 18}Figure 3: Object Identifier Assignment 💫
Full Copyright Statement 🎀
Copyright (C) The Internet Society (1998). 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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