D48=    #MAC  FFSTDESC                     [J.S.RAYNER.G4 ONLY  
 D4MW          FDESC    %A                  [ADDR OF ONE OF THE TABLES DESC WORDS
 D57G     MOD  LDX   0  0,%A 
 D5M6          SLC   0  7
 D66Q          ANDN  0  15                  [EXTRACT LENGTH OF TABLE 
 D6LB          NGX   0  0
 D762          ANDX  %A 0                   [ADDR OF FIRST DESC WORK 
 D7KL    #NOR