## Overview - MHS Directory User Package

The message handling system (MHS) directory user package (MDUP) contains definitions to support the use of the directory in accordance with the standard 1988 X.400 User Agents and MTAs for name resolution, distribution list (DL) expansion, and capability assessment. The definitions are based upon the attribute types and syntaxes specified in X.402, Annex A.

The MDUP is an optional package that can be used by the XDS interface. Applications must negotiate use of this package with ds_version( ) before using any of the MDUP features. If an application attempts to use features specific to the package without first negotiating its use, an appropriate error (for example, OM_NO_SUCH_CLASS) is returned by the object management (OM) function.

The object identifier associated with the MDUP is

{iso(1) identified-organization(3) icd-ecma(0012) member-company(2)
dec(1011) xopen(28) mdup(3)}

It takes the following encoding:

\x2B\xC\x2\x87\x73\x1C\x3

This identifier is represented by the constant DS_MHS_DIR_USER_PKG. The C constants associated with this package are defined in the xdsmdup.h, xmhp.h, and xmsga.h header files.

The concepts and notation used are first mentioned in XDS Class Definitions. They are also fully explained in Information Syntaxes, XOM Service Interface , and Object Management Package . The attribute types are introduced first, followed by the object classes. Next, the OM class hierarchy and OM class definitions required to support the new attribute types are described.

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