! *** 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
    
    
      DECLARE LONG CONSTANT S2DGB$K_OP_XCDB32 = 1  !  Diagnose opcode for 32-bit buffers
      DECLARE LONG CONSTANT S2DGB$K_OP_XCDB64 = 2  !  Diagnose opcode for 64-bit buffers
      DECLARE LONG CONSTANT S2DGB$M_READ = x'00000001'
      DECLARE LONG CONSTANT S2DGB$M_DISCPRIV = x'00000002'
      DECLARE LONG CONSTANT S2DGB$M_SYNCHRONOUS = x'00000004'
      DECLARE LONG CONSTANT S2DGB$M_OBSOLETE1 = x'00000008'
      DECLARE LONG CONSTANT S2DGB$M_TAGGED_REQ = x'00000010'
      DECLARE LONG CONSTANT S2DGB$M_TAG = x'000000E0'
      DECLARE LONG CONSTANT S2DGB$K_TAG_POSITION = 5  !  Bit offset of TAG bitfield 
      DECLARE LONG CONSTANT S2DGB$K_SIMPLE = 0  !  Simple queue tag
      DECLARE LONG CONSTANT S2DGB$K_ORDERED = 1  !  Ordered queue tag
      DECLARE LONG CONSTANT S2DGB$K_EXPRESS = 2  !  Head of Queue queue tag
      DECLARE LONG CONSTANT S2DGB$M_AUTOSENSE = x'00000100'
      DECLARE LONG CONSTANT S2DGB$M_EXT_LUN = x'00000200'
      DECLARE LONG CONSTANT S2DGB$K_XCDB32_LENGTH = 60  !  Diagnose buffer length, 32-bit buffers
      DECLARE LONG CONSTANT S2DGB$K_XCDB64_LENGTH = 60  !  Diagnose buffer length, 64-bit buffers
      DECLARE LONG CONSTANT S2DGB$K_XCDB_MIN_LENGTH = 60  !  Minimum s2gdb length
      DECLARE LONG CONSTANT S2DGB$K_EXT_XCDB_MIN_LENGTH = 68  !  Length w/external LUN
      DECLARE LONG CONSTANT S2DGB$S_S2DGB = 72
      record S2DGB
         LONG S2DGB$L_OPCODE                !  Diagnose opcode
         group S2DGB$R_FLAGS_OVERLAY
            variant
               case
                  group S2DGB$R_FILL_13_
                     variant
                     case
                        LONG S2DGB$L_FLAGS
                     case
                        group S2DGB$R_FILL_14_
                            !  Read operation
                            !  DiscPriv val in Identigy msg
                            !  Synchronous xfers permitted
                            !  (Ignored)
                            !  Use TCQ
                            !  Queue tag value type
                            !  Return Autosense data
                            !  Use externally-supplied LUN
                           WORD READ_bits   ! COMMENT ADDED BY SDL - READ_bits contains bits READ through FILL_15_
                        end group S2DGB$R_FILL_14_
                     end variant
                  end group S2DGB$R_FILL_13_
            end variant
         end group S2DGB$R_FLAGS_OVERLAY
         group S2DGB$R_REMAINING_OVERLAY
            variant
               case
                  group S2DGB$R_LAYOUT_32BIT
    !  Fields in this structure are valid if and
    !  only if s2dgb$l_opcode = S2DGB$K_OP_XCDB32
                     LONG S2DGB$L_32CDBADDR  !  32-bit addr of Cmd Desc Blk
                     LONG S2DGB$L_32CDBLEN  !  Length of CDB in bytes
                     LONG S2DGB$L_32DATADDR  !  32-bit addr of DATAIN or DATAOUT address
                     LONG S2DGB$L_32DATLEN  !  Length of DATAIN or DATAOUT buffer in bytes
                     LONG S2DGB$L_32PADCNT  !  Number of pad bytes required.
                     LONG S2DGB$L_32PHSTMO  !  Phase timeout value in seconds
                     LONG S2DGB$L_32DSCTMO  !  Disconnect timeout value in seconds
                     LONG S2DGB$L_32SENSEADDR  !  32-bit addr of Autosense buffer
                     LONG S2DGB$L_32SENSELEN  !  Length of Autosense buffer in bytes
                     LONG S2DGB$L_RESERVED1  !  Reserved field
                     LONG S2DGB$L_RESERVED2  !  Reserved field
                     LONG S2DGB$L_RESERVED3  !  Reserved field
                     LONG S2DGB$L_RESERVED4  !  Reserved field
                  end group S2DGB$R_LAYOUT_32BIT
               case
                  group S2DGB$R_LAYOUT_64BIT
    !  Fields in this structure are valid if and
    !  only if s2dgb$l_opcode = S2DGB$K_OP_XCDB64
                     BASIC$QUADWORD S2DGB$PQ_64CDBADDR  !  64-bit addr of Cmd Desc Blk
                     BASIC$QUADWORD S2DGB$PQ_64DATADDR  !  64-bit addr of DATAIN or DATAOUT address
                     BASIC$QUADWORD S2DGB$PQ_64SENSEADDR  !  64-bit addr of Autosense buffer
                     LONG S2DGB$L_64CDBLEN  !  Length of CDB in bytes
                     LONG S2DGB$L_64DATLEN  !  Length of DATAIN or DATAOUT buffer in bytes
                     LONG S2DGB$L_64SENSELEN  !  Length of Autosense buffer in bytes
                     LONG S2DGB$L_64PADCNT  !  Number of pad bytes required.
                     LONG S2DGB$L_64PHSTMO  !  Phase timeout value in seconds
                     LONG S2DGB$L_64DSCTMO  !  Disconnect timeout value in seconds
                     LONG S2DGB$L_RESERVED_1  !  Reserved field
                  end group S2DGB$R_LAYOUT_64BIT
            end variant
         end group S2DGB$R_REMAINING_OVERLAY
         BASIC$QUADWORD S2DGB$Q_EXT_LUN     !  External LUN
         BYTE S2DGB$B_FILL_16_ ( 3 )
      end record S2DGB