! *** PREDECLARED TYPES
     
      %IF %DECLARED ( %BASIC$QUADWORD_DECLARED ) = 0 %THEN
         RECORD BASIC$QUADWORD
            LONG FILL ( 2 )
         END RECORD
         %LET %BASIC$QUADWORD_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$OCTAWORD_DECLARED ) = 0 %THEN
         RECORD BASIC$OCTAWORD
            LONG FILL ( 4 )
         END RECORD
         %LET %BASIC$OCTAWORD_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$HFLOAT_AXP_DECLARED ) = 0 %THEN
         RECORD BASIC$HFLOAT_AXP
            LONG FILL ( 4 )
         END RECORD
         %LET %BASIC$HFLOAT_AXP_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$F_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$F_FLOATING_COMPLEX
            SINGLE REAL_PART
            SINGLE IMAGINARY_PART
         END RECORD
         %LET %BASIC$F_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$D_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$D_FLOATING_COMPLEX
            DOUBLE REAL_PART
            DOUBLE IMAGINARY_PART
         END RECORD
         %LET %BASIC$D_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$G_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$G_FLOATING_COMPLEX
            GFLOAT REAL_PART
            GFLOAT IMAGINARY_PART
         END RECORD
         %LET %BASIC$G_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$H_FLOAT_AXP_CMPLX_DCL ) = 0 %THEN
         RECORD BASIC$H_FLOATING_COMPLEX_AXP
            BASIC$HFLOAT_AXP REAL_PART
            BASIC$HFLOAT_AXP IMAGINARY_PART
         END RECORD
         %LET %BASIC$H_FLOAT_AXP_CMPLX_DCL = 1
      %END %IF
    
    
    ! 
    !         file header characteristics xab definitions
    !                 $xabfhcdef
    ! 
    !   the fields of this xab cannot be rearranged since
    !   they correspond to an on-disk structure
    ! 
      DECLARE LONG CONSTANT XAB$C_FHC = 29  !  xabfhc id code
      DECLARE LONG CONSTANT XAB$M_FTN = x'00000001'
      DECLARE LONG CONSTANT XAB$M_CR = x'00000002'
      DECLARE LONG CONSTANT XAB$M_PRN = x'00000004'
      DECLARE LONG CONSTANT XAB$M_BLK = x'00000008'
      DECLARE LONG CONSTANT XAB$M_GBC_PERCENT = x'00000001'
      DECLARE LONG CONSTANT XAB$M_GBC_DEFAULT = x'00000002'
      DECLARE LONG CONSTANT XAB$S_XABFHCDEF = 44
      record XABFHCDEF
         BYTE XABFHCDEF$$_FILL_1
         BYTE XABFHCDEF$$_FILL_2
         WORD XABFHCDEF$$_FILL_3
         LONG XABFHCDEF$$_FILL_4            ! 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
         group XAB$R_FILL_9_
            variant
               case
                  BYTE XAB$B_ATR            !  record attributes
               case
                  group XAB$R_FILL_10_
                      !  fortran carriage-ctl
                      !  lf-record-cr carriage ctl
                      !  print-file carriage ctl
                      !  records don't cross block boundaries
                     BYTE FTN_bits   ! COMMENT ADDED BY SDL - FTN_bits contains bits FTN through FILL_11_
                  end group XAB$R_FILL_10_
            end variant
         end group XAB$R_FILL_9_
         WORD XAB$W_LRL                     !  longest record's length
         group XAB$R_HBK_OVERLAY
            variant
               case
                  LONG XAB$L_HBK            !  hi vbn allocated
    !  (n.b. reversed on disk?)
               case
                  group XAB$R_HBK_FIELDS
                     WORD XAB$W_HBK0
                     WORD XAB$W_HBK2
                  end group XAB$R_HBK_FIELDS
            end variant
         end group XAB$R_HBK_OVERLAY
         group XAB$R_EBK_OVERLAY
            variant
               case
                  LONG XAB$L_EBK            !  eof vbn
    !  (n.b. reversed on disk)
               case
                  group XAB$R_EBK_FIELDS
                     WORD XAB$W_EBK0
                     WORD XAB$W_EBK2
                  end group XAB$R_EBK_FIELDS
            end variant
         end group XAB$R_EBK_OVERLAY
         WORD XAB$W_FFB                     !  first free byte in eof block
         BYTE XABFHCDEF$$_FILL_5            !  bucket size for fhc ( note: field name is bkz,
    !  defined above in $xabdef,since it is shared by the fhc
    !  xab and has the same offset, of course)
    ! -----*****
    ! HAVE BEEN DEFINED BY $XABDEF
    !  defined above in $xabdef, since it is shared
    !  by the all xab)
         BYTE XAB$B_HSZ                     !  header size for vfc
         WORD XAB$W_MRZ                     !  max record size
         WORD XAB$W_DXQ                     !  default extend quantity
         group XAB$R_GBC16_OVERLAY
            variant
               case
                  WORD XAB$W_GBC            !  global buffer count (original word)
               case
                  WORD XAB$W_GBC16          !  Alias 
            end variant
         end group XAB$R_GBC16_OVERLAY
         group XAB$R_RECATTR_FLAGS_OVERLAY
            variant
               case
                  BYTE XAB$B_RECATTR_FLAGS  !  flags for record attribute area
               case
                  group XAB$R_RECATTR_FLAGS_BITS
                      !  Interpret value in GBC32 as percent instead of count
                      !  RMS should set default for GBC at runtime and ignore
    !    any values in GBC16 or GBC32
                      !  Reserved for future use
                     BYTE GBC_PERCENT_bits   ! COMMENT ADDED BY SDL - GBC_PERCENT_bits contains bits GBC_PERCENT through FILL_7
                  end group XAB$R_RECATTR_FLAGS_BITS
            end variant
         end group XAB$R_RECATTR_FLAGS_OVERLAY
         BYTE XABFHCDEF$$_FILL_8            !  reserved for future use (possible flags word union)
         LONG XAB$L_GBC32                   !  longword implementation of global buffer count
         BYTE XABFHCDEF$$_FILL_6 ( 1 to 2 )    !  spare space documented as unused in I/O REF 
         WORD XAB$W_VERLIMIT                !  version limit for file.
    ! -----*****
         LONG XAB$L_SBN                     !  starting lbn if contiguous
      end record XABFHCDEF
    
    !  basealign on aggregate XABFHCDEF operates after aggregate end
      DECLARE LONG CONSTANT XAB$K_FHCLEN = 44  !  length of xabfhc
      DECLARE LONG CONSTANT XAB$C_FHCLEN = 44  !  length of xabfhc