1.2  Index of message types by name

     Change indicators

     a plus sign (+)    for an addition
     an asterisk (*)    for an amendment to structure
     a hash sign (#)    for changes to names
     a vertical bar (|) for changes to text for descriptions,
                        notes and functions
     a minus sign (-)   for a deletion
     an X sign (X)      for marked for deletion

   Code  Name                                      Version Rev

   AVLREQ Availability request - interactive message     1        1
   AVLRSP Availability response - interactive message    1        1
*  RESREQ Reservation request - interactive message      1        2
*  RESRSP Reservation response - interactive message     1        3