X400: X.400, X.200, and X.25 Acronyms

The information in this article applies to:

• Microsoft Mail Gateway to X.400, version 3.0

Here is a list of common X.400, X.200, and X.25 acronyms:

   Acronym  Description
   -------  -----------

   ADMD     Administrative management domain
   AEA      Activity end acknowledge
   APDU     Application protocol data unit
   AS       Activity start
   ASCII    American Standard Code for Information Interchange
   ASN      Abstract syntax notation
   AU       Access unit
   BSC      Bisynchronous communications
   CCITT    Consultative Committee for International Telephone and
            Telegraph
   CRC      Cyclic redundancy check
   DCE      Data communications equipment
   DL       Directory listing
   DSA      Directory system agent
   DTE      Data terminal equipment
   DUA      Directory user agent
   EIT      Encoding information type
   HDLC     High-level data link communications
   IA5      International Alphabet 5
   IPM      Interpersonal message
   ISO      International Standards Organization
   MD       Management domain
   MHS      Message handling system
   MS       Message store
   MTA      Message transfer agent
   O/R      Originator/recipient
   OSI      Open Systems Interconnection
   OSTC     Open System Testing Consortium
   PAD      Packet assembler dissembler
   PDAU     Physical data access unit
   PRMD     Private management domain
   SPDU     Session protocol data unit
   TPDU     Transport protocol data unit
   UA       User agent