!*** MODULE $XABFHCDEF ***
!DEC$ OPTIONS/ALIGN=(RECORDS=PACKED,COMMONS=PACKED)/NOWARN
 ! 
 !         file header characteristics xab definitions
 !                 $xabfhcdef
 ! 
 !   the fields of this xab cannot be rearranged since
 !   they correspond to an on-disk structure
 ! 
	PARAMETER XAB$C_FHC = '0000001D'X	 !  xabfhc id code
	PARAMETER XAB$M_FTN = '00000001'X
	PARAMETER XAB$M_CR = '00000002'X
	PARAMETER XAB$M_PRN = '00000004'X
	PARAMETER XAB$M_BLK = '00000008'X
	PARAMETER XAB$M_GBC_PERCENT = '00000001'X
	PARAMETER XAB$M_GBC_DEFAULT = '00000002'X
	STRUCTURE /XABFHCDEF/
	    BYTE      %FILL
	    BYTE      %FILL
	    INTEGER*2 %FILL
	    INTEGER*4 %FILL				 ! HAS SAME COD, BLN, SPARE AND NXT FIELD
 ! THESE 4 FIELDS ARE COMMON TO ALL XABS AND
 ! HAVE BEEN DEFINED BY $XABDEF
	    BYTE      XAB$B_RFO			 !  record format and file org
	    UNION
	        MAP
	        BYTE      XAB$B_ATR			 !  record attributes
	        END MAP
	        MAP
	            PARAMETER XAB$S_FTN = 1
	            PARAMETER XAB$V_FTN = 0			 !  fortran carriage-ctl
	            PARAMETER XAB$S_CR = 1
	            PARAMETER XAB$V_CR = 1			 !  lf-record-cr carriage ctl
	            PARAMETER XAB$S_PRN = 1
	            PARAMETER XAB$V_PRN = 2			 !  print-file carriage ctl
	            PARAMETER XAB$S_BLK = 1
	            PARAMETER XAB$V_BLK = 3			 !  records don't cross block boundaries
	        BYTE %FILL (1)
	        END MAP
	    END UNION
	    INTEGER*2 XAB$W_LRL			 !  longest record's length
	    UNION
	        MAP
	        INTEGER*4 XAB$L_HBK			 !  hi vbn allocated
	        END MAP
 !  (n.b. reversed on disk!)
	        MAP
	            INTEGER*2 XAB$W_HBK0
	            INTEGER*2 XAB$W_HBK2
	        END MAP
	    END UNION
	    UNION
	        MAP
	        INTEGER*4 XAB$L_EBK			 !  eof vbn
	        END MAP
 !  (n.b. reversed on disk)
	        MAP
	            INTEGER*2 XAB$W_EBK0
	            INTEGER*2 XAB$W_EBK2
	        END MAP
	    END UNION
	    INTEGER*2 XAB$W_FFB			 !  first free byte in eof block
	    BYTE      %FILL				 !  bucket size for fhc ( note: field name is bkz,
 !  defined above in $xabdef,since it is shared by the fhc
 !  xab and has the same offset, of course)
 ! -----*****
 ! HAVE BEEN DEFINED BY $XABDEF
 !  defined above in $xabdef, since it is shared
 !  by the all xab)
	    BYTE      XAB$B_HSZ			 !  header size for vfc
	    INTEGER*2 XAB$W_MRZ			 !  max record size
	    INTEGER*2 XAB$W_DXQ			 !  default extend quantity
	    UNION
	        MAP
	        INTEGER*2 XAB$W_GBC			 !  global buffer count (original word)
	        END MAP
	        MAP
	        INTEGER*2 XAB$W_GBC16			 !  Alias 
	        END MAP
	    END UNION
	    UNION
	        MAP
	        BYTE      XAB$B_RECATTR_FLAGS		 !  flags for record attribute area
	        END MAP
	        MAP
	            PARAMETER XAB$S_GBC_PERCENT = 1
	            PARAMETER XAB$V_GBC_PERCENT = 0		 !  Interpret value in GBC32 as percent instead of count
	            PARAMETER XAB$S_GBC_DEFAULT = 1
	            PARAMETER XAB$V_GBC_DEFAULT = 1		 !  RMS should set default for GBC at runtime and ignore
 !    any values in GBC16 or GBC32
	        BYTE %FILL (1)
	        END MAP
	    END UNION
	    BYTE      %FILL				 !  reserved for future use (possible flags word union)
	    INTEGER*4 XAB$L_GBC32			 !  longword implementation of global buffer count
	    BYTE      %FILL(1:2)			 !  spare space documented as unused in I/O REF 
	    INTEGER*2 XAB$W_VERLIMIT		 !  version limit for file.
 ! -----*****
	    INTEGER*4 XAB$L_SBN			 !  starting lbn if contiguous
	END STRUCTURE	! XABFHCDEF
 !  basealign on aggregate XABFHCDEF operates after aggregate end
	PARAMETER XAB$K_FHCLEN = '0000002C'X	 !  length of xabfhc
	PARAMETER XAB$C_FHCLEN = '0000002C'X	 !  length of xabfhc
!DEC$ END OPTIONS