NAME
       UMSErrTxt -- Return a string describing the last error.

   SYNOPSIS
       text = UMSErrTxt( login )
        D0                D2

       STRPTR UMSErrTxt( LONG );

   FUNCTION
         When an UMS functions fails and/or  UMSErrNum() returns a nonzero
       value,  you  should  use  this  routine  to  get  a  brief English
       description of the last error.
         Interactive  programs  should  display  this  text  to the user.
       Non-interactive programs should use this text in their logfile.

   INPUTS
       login - Login handle as returned by  UMSLogin() or  UMSRLogin().

   RESULT
       text - Pointer to a String.

   NOTES
         This is similiar to dos.library/Fault(), but it doesn't copy any
       string, it just returns a pointer.

         You may NEVER change the string returned by UMSErrTxt()!