NAME
       UMSLogin -- Open the UMS MB for a certain user.

   SYNOPSIS
       login = UMSLogin( user, passwd )
         D0               D2     D3

       LONG UMSLogin( STRPTR, STRPTR );

   FUNCTION
         Opens  the  MB,  checking  the  password and returning a 'login'
       handle  when  successful.   The given 'user'-name must be known to
       the MBP and the password 'passwd' must match.  If the MBP does not
       already run, it will be automatically started.
         All  other  functions  in  ums.library  requiry  a valid 'login'
       handle to work.

   INPUTS
       user   - Name or 'alias' of an user known to the MBP.
       passwd - The user's correct password. A pointer to the null-string
                is allowed, NULL itself isn't.

   RESULT
       login  - Internally used handle to track and remember resources
                associated  with each  Login.   Different  for a single
                user's  multiple  Logins.  One Login may be used only by
                one process at a time.
                Greater 0 on success, lower or equal 0 on failure.

   EXAMPLE
       long login = UMSLogin( "Martin Horneffer", "secret");

   NOTES
         If  multiple  MBPs  are running on the same machine, you may use
        UMSRLogin() to specify which one to use.

   SEE ALSO
        UMSRLogin(),  UMSLogout()