$VER: 10.21 (28-Aug-93)

       COPYRIGHT

         This document is (C) 1992 by Martin Horneffer.

         It may freely be copied and distributed, as long as the text is
       unchanged and this copyright notice is left intact.

       GENERAL

         UMS stands for "Universal Message System".

         This  means  that  UMS  allows  to  treat  and read all kinds of
       messages  ('e-mail'  and 'news') as universally and efficiently as
       possible.

         The  user  should  not need to care about what network a message
       comes  from  or goes to/through and what format is used, he or she
       should be able to concentrate totally on the messages' contents.

         In order to achieve this goal, UMS does two things:

         1) define an universal format for messages where messages in all
       formats  and  from  all  networks can be stored in without loss of
       information and nevertheless being randomly interchangeable.

         2) implement  a central, network-independent database-mamagement
       that  allows to store and read/retrieve messages in the UMS format
       as efficiently as possible.

         For  the message format, please read the separate documentation.

         The  implementation  of  the  Message  Base Processor ('MBP') is
       based  on  the server/client- concept.  Clients address the server
       to  get  or  put  messages.   The  server  manages the storage and
       retrieval   of   messages  and  controls  the  different  client's
       access-rights  to the system.  The common interface between client
       and server is a set of functions described in this document.

         Clients are
         -  simple  USERS  that  read  and write messages (using programs
       called 'newsreaders'),
         -  a  special  kind  of  user, the 'SYSOP', which has additional
       rights and tools to administer the system,
         -  IMPORTERS,  that get messages form other systems and put them
       into the local system after converting them to the UMS format, and
         -  EXPORTERS,  that  look for all NEW messages in the system and
       send them to other systems after converting them into the specific
       format.

         The  MBP  controls  which user may read what message and, in the
       same  way, which exporter needs to export or forward what message.
       It  cares  about whether a message can or cannot be correctly sent
       to its destination.
         The  MBP  also  performs  dupe-checking  and  reply-chaining  on
       Message-IDs.


       TAGS

         UMS uses some bit-masking in tag values to indicate some special
       types of tag data:

         if  bit 13 is set (tag & 0x2000), the tag data is a STRPTR, i.e.
       a pointer to a null-terminated string.

         if  bit  14 is set (tag & 0x4000), the tag is considered a 'var-
       parameter'  (e.g.  LONG *).  I.e.  the tag.data entry must contain
       a  pointer  to  the  real  data,  which will be set/changed by the
       called function.

         if both bits 13 and 14 are set ((tag & 0x6000)==0x6000), the tag
       is a pointer to a string pointer which will be set/changed (STRPTR
       *).

         if none of these bits is set, the data in most cases is a simple
       integer parameter (e.g.  LONG or LONGBITS).