bifsub	struc		;parms for substitution from keysquare
;bp-24	dw	?	 N**2
;bp-22	dw		 ciphertext top or bottom line origin
;bp-20	dw	?	 return code, 0 = no conflicts, -1 = conflicts
;bp-18	db	?	 flaga
;			 01 = conflict detected
;			 02 = this block is odd length
;			 04 = this letter index is odd
;			 08 = ciphertext bottom line
;			 10 = use column key letters, 00 use row key letters
;			 80 = plaintext / keysquare coordinate conflict
;bp-17	db		 flagb for filler
;bp-16	dw	?	 length of a short block
;bp-14	dw	?	 length of a full block
;bp-12	dw	?	 number of full blocks
;bp-10	dw	?	 start of top row coordinates
;bp-8	dw	?	 key start offset
;bp-6	dw	?	 col start offset
;bp-4	dw	?	 row start offset
;bp-2	dw	?	 5 for address arith
	dw	?	;bp save
	dd	?	;return address
keyp2	dd	?	;->keysquare parms
bifp	dd	?	;->bifid parms
bifsub	ends