*COMDECK BACKBUF
# 
 FIXED BUFFER FOR QUEUEING DOWNLINE BACKS 
# 
 DEF MAXBBUFSIZE#24#;                  # MAXIMUM NUMBER OF ENTRIES IN  #
                                       # DOWNLINE BACK QUEUE           #
 COMMON BACKBUF;
   BEGIN
   ARRAY BBUFHEAD S(1);                # MARK POSITION OF BUFFER IN DMP#
     BEGIN
     ITEM BBUFNAME   C(00,00,07) = ["BACKBUF"];  # NAME OF BUFFER      #
     ITEM BBUFEND    U(00,42,18) = [O"777777"];  # TERMINATE HEADER    #
     END
   ITEM BACKBFWA;                      # FWA OF BACK BUFFER            #
   ITEM BACKBLWA;                      # LWA+1 OF BACK BUFFER          #
   ITEM BACKFFREE;                     # POINTER TO FIRST FREE ENTRY   #
  
   ARRAY BACKBUFT [0:MAXBBUFSIZE] S(3);  # BUFFER FOR DOWNLINE BACKS   #
     BEGIN
     ITEM BACKFPTR   U(00,42,18);      # POINTER TO NEXT FREE ENTRY    #
     ITEM BACKHWORD  U(00,00,60);      # BACK BUFFER POINTER WORD      #
     ITEM BACKBLKID  U(01,00,06) = [MAXBBUFSIZE(POBIDVALUE),POBIDVALUE];
     ITEM BACKBLKSZ  U(01,06,18) = [MAXBBUFSIZE(2),2];
     ITEM BACKBLKRS  U(01,24,36) = [MAXBBUFSIZE(0),0];
     ITEM BACKBLKWD  U(01,00,60); 
     ITEM BACKNHEAD  U(02,00,24); 
     ITEM BACKNWORD  U(02,00,60) = [MAXBBUFSIZE(0),0];
     END
   END
