9**= ...[??? STEPBAC SECT CENT FGN 9 DOC
 CWSB    # THIS MACRO STEPS BACK THE ONR OF A PROG MEMBER.%A-ADDRESS OF X0   
 CXRL    #     MARK 4 ONWARDS VERSION OF STEPBAC 
 CY?=    #MAC  STEPBAC   
 CYQW          LDX 0 %A  
 C^=G          STO 0 JWSP1   
 C^Q6          MOD   LDX 0 9,%A  
 D29Q          SLC   0  3
 D2PB          ANDN  0  1
 D392          ADN   0  1
 D3NL          SMO JWSP1 
 D48=          SBS 0 8   
 D4MW    #NOR