! *** 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 MMG$C_VAX_PAGE_SIZE = 512  !  SIZE OF VAX PAGE
      DECLARE LONG CONSTANT MMG$C_ALPHA_MAX_PAGE_SIZE = 65536  !  MAX. PAGE SIZE
      DECLARE LONG CONSTANT IOC$C_DISK_BLKSIZ = 512  !  STANDARD DISK BLOCK SIZE
      DECLARE LONG CONSTANT IOC$C_CD_DVD_BLKSIZ = 2048  !  Typical CD and DVD sector size
      DECLARE LONG CONSTANT IOC$M_BLOCK_BYTEMASK = x'000001FF'
      DECLARE LONG CONSTANT IOC$M_BLOCK_BLKNUM = x'FFFFFE00'
      DECLARE LONG CONSTANT IOC$S_BLOCKDEF = 4
      record BLOCKDEF
         variant
            case
               group IOC$R_BLOCKDEF_BITS0
                   ! BYTE VIELD 
                   ! BLOCK NUMBER 
                  LONG BLOCK_BYTEMASK_bits   ! COMMENT ADDED BY SDL - BLOCK_BYTEMASK_bits contains bits BLOCK_BYTEMASK through  &
 ! BLOCK_BLKNUM
               end group IOC$R_BLOCKDEF_BITS0
         end variant
      end record BLOCKDEF
    
      DECLARE LONG CONSTANT IOC$M_DVDBLK_BYTEMASK = x'000007FF'
      DECLARE LONG CONSTANT IOC$M_DVDBLK_BLKNUM = x'FFFFF800'
      DECLARE LONG CONSTANT IOC$S_DVDBLKDEF = 4
      record DVDBLKDEF
         variant
            case
               group IOC$R_DVDBLKDEF_BITS0
                   !  CD/DVD Vield 
                   !  CD/DVD Block Number
                  LONG DVDBLK_BYTEMASK_bits   ! COMMENT ADDED BY SDL - DVDBLK_BYTEMASK_bits contains bits DVDBLK_BYTEMASK through  &
 ! DVDBLK_BLKNUM
               end group IOC$R_DVDBLKDEF_BITS0
         end variant
      end record DVDBLKDEF