Network Working Group                                           S. Kille
Request for Comments: 1836                              ISODE Consortium
Category: Experimental                                       August 1995

             Representing the O/R Address hierarchy in the
                    X.500 Directory Information Tree

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.


   This document defines a representation of the O/R Address hierarchy
   in the Directory Information Tree [6, 1].  This is useful for a range
   of purposes, including:

o  Support for MHS Routing [4].

o  Support for X.400/RFC 822 address mappings [2, 5].

                 Object Class               Mandatory
                 ------------               ---------
                 mHSCountry                 M
                 aDMD                       M
                 pRMD                       O
                 mHSX121                    O
                 mHSNumericUserIdentifier   O
                 mHSOrganization            O
                 mHSOrganizationalUnit      O
                 mHSPerson                  O
                 mHSNamedObject             O
                 mHSTerminalID              O
                 mHSDomainDefinedAttribute  O

         Table 1:  Order of O/R Address Directory Components

1.  The O/R Address Hierarchy

   An O/R Address hierarchy is represented in the X.500 directory by
   associating directory name components with O/R Address components.
   An example of this is given in Figure 1.  The object classes and
   attributes required to support this representation are defined in
   Figure 2.  The schema, which defines the hierarchy in which these

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

   objects are represented in the directory information tree is
   specified in Table 1.  A given object class defined in the table will
   always be higher in the DIT than an object class defined lower down
   the table.  Valid combinations 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    |< -----------|    |
                +----------+             +----+
     | MHS-Org    |
            \  OU=CS
              | MHS-OU    |

                    Figure 1:  Example O/R Address Tree

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

  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,

    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}

    SUBCLASS OF {top}
    ID oc-admd}

    SUBTYPE OF name
    WITH SYNTAX DirectoryString {ub-domain-name-length}             30
    ID at-admd-name}

    SUBCLASS OF {top}
    ID oc-prmd}

    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}

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

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|
    ID oc-mhs-person}                                               70

mHSSurname ATTRIBUTE ::= {
    SUBTYPE OF surname
    WITH SYNTAX DirectoryString {ub-surname-lenght}
    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}

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

mHSCommonName ATTRIBUTE ::= {
    SUBTYPE OF commonName
    WITH SYNTAX DirectoryString {ub-common-name-length}
    ID at-mhs-common-name}                                         100

    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}
    ID oc-mhs-domain-defined-attribute}

mHSDomainDefinedAttributeType ATTRIBUTE ::= {
    SUBTYPE OF name                                                120
    WITH SYNTAX DirectoryString {ub-domain-defined-attribute-type-length}
    ID at-mhs-domain-defined-attribute-type}

mHSDomainDefinedAttributeValue ATTRIBUTE ::= {
    SUBTYPE OF name
    WITH SYNTAX DirectoryString {ub-domain-defined-attribute-value-length}
    ID at-mhs-domain-defined-attribute-value}
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}

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

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

The hierarchy is defined so that:

1.  The representation is defined so that it is straightforward to
    make a mechanical transformation in either direction.  This
    requires that each node is named by an attribute whose type can
    determine the mapping.

2.  Where there are multiple domain defined attributes, the first in
    the sequence is the most significant.

3.  Physical Delivery (postal) addresses are not represented in this
    hierarchy.  This is primarily because physical delivery can be
    handled by the Access Unit routing mechanisms defined in [4], and
    there is no need for this representation.

4.  Terminal and network forms of address are not handled, except for
    X.121 form, which is useful for addressing faxes.

5.  MHSCountry is defined as a subclass of Country, and so the same
    entry will be used for MHS Routing as for the rest of the DIT.

6.  The numeric country code will be an alias.

7.  ADMD will always be present in the hierarchy.  This is true in the
    case of " " and of "0".  This facilitates an easy mechanical
    transformation between the two forms of address.

8.  Each node is named by the relevant part of the O/R Address.

9.  Aliases may be used in other parts of the tree, in order to
    normalise 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

10. Domain Defined Attributes are named by a multi-valued RDN
    (Relative Distinguished Name), consisting of the type and value.
    This is done so that standard attribute syntaxes can be used.

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

11. 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.  This is
    so that direct lookup of the name will work, independent of the
    variant used.  When both are present in an O/R Address being
    looked up, either may be used to construct the distinguished name.

12. Personal name is handled by use of the mHSPerson object class.
    Each of the components 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) are given in Table 2.  Where there
   are multiple Organizational Units or Domain Defined Attributes, each
   component is mapped onto a single X.500 entry.

   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
       organisational or departmental fax gateway service.

O/R Address  Object Class               Naming Attribute
-----------  ------------               ----------------
C            mHSCountry                 countryName
A            aDMD                       aDMDName
P            pRMD                       pRMDName
O            mHSOrganization            mHSOrganizationName
OU/OU1/OU2   mHSOrganizationalUnit      mHSOrganizationalUnitName
PN           mHSPerson                  personName
CN           mHSNamedObject             mHSCommonName
X121         mHSX121                    mHSX121Address
T-ID         mHSTerminalID              mHSTerminalIDName
UA-ID        mHSNumericUserIdentifier   mHSNumericUserIdentifierName
DDA          mHSDomainDefinedAttribute  mHSDomainDefinedAttributeType

         Table 2:  O/R Address relationship to Directory Name

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

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

   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:


            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-ID

              Table 3:  Keywords for String DN Representation

   PRMD=UK.AC, ADMD=Gold 400, C=GB

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

4.  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 to generate an equivalent directory name.  This
   mapping is only used for selected types of O/R Address:

   o  Mnemonic form

   o  Numeric form

   o  Terminal form, where country is present and X121 addressing is

   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:

   1.  A DDA generates a multi-valued RDN

   2.  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.  Acknowledgements

   Acknowledgements for work on this document are given in [4].

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995


   [1] The Directory --- overview of concepts, models and services,
       1993. CCITT X.500 Series Recommendations.

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

   [3] Kille, S., "A String Representation of Distinguished Names",
       RFC 1779, Department of Computer Science, University College
       London, March 1995.

   [4] Kille, S., "MHS Use of the X.500 Directory to Support MHS
       Routing, RFC 1801, ISODE Consortium, June 1995.

   [5] Kille, S., "Use of the X.500 Directory to Support Mapping between
       X.400 and RFC 822 Addresses, RFC 1838, ISODE Consortium,
       August 1995.

   [6] CCITT recommendations X.400 / ISO 10021, April 1988. CCITT
       SG 5/VII / ISO/IEC JTC1, Message Handling:  System and Service

7.  Security Considerations

   Security issues are not discussed in this memo.

8.  Author's Address

   Steve Kille
   ISODE Consortium
   The Dome
   The Square
   TW9 1DT

   Phone:  +44-81-332-9091
   Internet EMail:  S.Kille@ISODE.COM

   X.400:  I=S; S=Kille; O=ISODE Consortium; P=ISODE;
   A=Mailnet; C=FI;

   DN: CN=Steve Kille,
   O=ISODE Consortium, C=GB

   UFN: S. Kille, ISODE Consortium, GB

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RFC 1836             O/R Addresses in the X.500 DIT          August 1995

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

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