! *** 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
    
    
    ! +
    !  I/O FUNCTION CODE DEFINITIONS
    ! -
    ! 
    !  *** START PHYSICAL I/O FUNCTION CODES ***
    ! 
      DECLARE LONG CONSTANT IO$_NOP = 0     ! NO OPERATION 
      DECLARE LONG CONSTANT IO$_UNLOAD = 1  ! UNLOAD DRIVE 
      DECLARE LONG CONSTANT IO$_LOADMCODE = 1  ! LOAD MICROCODE 
      DECLARE LONG CONSTANT IO$_START_BUS = 1  ! START LAVC BUS
      DECLARE LONG CONSTANT IO$_SEEK = 2    ! SEEK CYLINDER 
      DECLARE LONG CONSTANT IO$_SPACEFILE = 2  ! SPACE FILES 
      DECLARE LONG CONSTANT IO$_STARTMPROC = 2  ! START MICROPROCESSOR 
      DECLARE LONG CONSTANT IO$_STOP_BUS = 2  ! STOP LAVC BUS
      DECLARE LONG CONSTANT IO$_RECAL = 3   ! RECALIBRATE DRIVE 
      DECLARE LONG CONSTANT IO$_DUPLEX = 3  ! ENTER DUPLEX MODE
      DECLARE LONG CONSTANT IO$_STOP = 3    ! STOP 
      DECLARE LONG CONSTANT IO$_DEF_COMP = 3  ! DEFINE NETWORK COMPONENT
      DECLARE LONG CONSTANT IO$_DRVCLR = 4  ! DRIVE CLEAR 
      DECLARE LONG CONSTANT IO$_INITIALIZE = 4  ! INITIALIZE 
      DECLARE LONG CONSTANT IO$_MIMIC = 4   ! ENTER MIMIC MODE
      DECLARE LONG CONSTANT IO$_DEF_COMP_LIST = 4  ! DEFINE NETWORK COMPONENT LIST
      DECLARE LONG CONSTANT IO$_FLUSH_ERROR = 4  ! FLUSH SCSI ERRORS
      DECLARE LONG CONSTANT IO$_RELEASE = 5  ! RELEASE PORT 
      DECLARE LONG CONSTANT IO$_SETCLOCKP = 5  ! SET CLOCK (PHYSICAL) 
      DECLARE LONG CONSTANT IO$_START_ANALYSIS = 5  ! START LAVC FAILURE ANALYSIS
      DECLARE LONG CONSTANT IO$_BIND = 5    ! BIND UNITS INTO A STORAGE POOL
      DECLARE LONG CONSTANT IO$_PATH_VERIFY = 5  ! VERIFY PATH TO DEVICE 
      DECLARE LONG CONSTANT IO$_OFFSET = 6  ! OFFSET READ HEADS 
      DECLARE LONG CONSTANT IO$_ERASETAPE = 6  ! ERASE TAPE 
      DECLARE LONG CONSTANT IO$_STARTDATAP = 6  ! START DATA TRANSFER (PHYSICAL) 
      DECLARE LONG CONSTANT IO$_STOP_ANALYSIS = 6  ! STOP LAVC FAILURE ANALYSIS
      DECLARE LONG CONSTANT IO$_UNBIND = 6  ! REMOVE UNITS FROM A STORAGE POOL
      DECLARE LONG CONSTANT IO$_RETCENTER = 7  ! RETURN TO CENTERLINE 
      DECLARE LONG CONSTANT IO$_QSTOP = 7   ! QUEUE STOP REQUEST 
      DECLARE LONG CONSTANT IO$_START_MONITOR = 7  ! START LAVC CHANNEL MONITOR.
      DECLARE LONG CONSTANT IO$_CREDISK = 7  ! CREATE A DISK IN A STORAGE POOL
      DECLARE LONG CONSTANT IO$_LOCAL_DRAIN = 7  ! DRAIN LOCAL IO
      DECLARE LONG CONSTANT IO$_PACKACK = 8  ! PACK ACKNOWLEDGE 
      DECLARE LONG CONSTANT IO$_STOP_MONITOR = 8  ! STOP LAVC CHANNEL MONITOR.
      DECLARE LONG CONSTANT IO$_SEARCH = 9  ! SEARCH FOR SECTOR 
      DECLARE LONG CONSTANT IO$_SPACERECORD = 9  ! SPACE RECORDS 
      DECLARE LONG CONSTANT IO$_READRCT = 9  ! READ REPLACEMENT ? CACHING TABLE
      DECLARE LONG CONSTANT IO$_REMDISK = 9  ! REMOVE A DISK FROM A STORAGE POOL
      DECLARE LONG CONSTANT IO$_WRITECHECK = 10  ! WRITE CHECK DATA 
      DECLARE LONG CONSTANT IO$_EXPORT = 10  ! EXPORT A DISK FROM A STORAGE POOL
      DECLARE LONG CONSTANT IO$_WRITEPBLK = 11  ! WRITE PHYSICAL BLOCK 
      DECLARE LONG CONSTANT IO$_READPBLK = 12  ! READ PHYSICAL BLOCK 
      DECLARE LONG CONSTANT IO$_WRITEHEAD = 13  ! WRITE HEADER AND DATA 
      DECLARE LONG CONSTANT IO$_RDSTATS = 13  ! READ STATISTICS 
      DECLARE LONG CONSTANT IO$_CRESHAD = 13  ! CREATE A SHADOW SET
      DECLARE LONG CONSTANT IO$_READHEAD = 14  ! READ HEADER AND DATA 
      DECLARE LONG CONSTANT IO$_ADDSHAD = 14  ! ADD MEMBER TO SHADOW SET
      DECLARE LONG CONSTANT IO$_WRITETRACKD = 15  ! WRITE TRACK DATA 
      DECLARE LONG CONSTANT IO$_COPYSHAD = 15  ! PERFORM SHADOW SET COPY OPERATIONS
      DECLARE LONG CONSTANT IO$_READTRACKD = 16  ! READ TRACK DATA 
      DECLARE LONG CONSTANT IO$_REMSHAD = 16  ! REMOVE MEMBER FROM SHADOW SET
      DECLARE LONG CONSTANT IO$_AVAILABLE = 17  ! AVAILABLE (DISK AND TAPE CLASS) 
      DECLARE LONG CONSTANT IO$_SETPRFPATH = 18  ! SET PREFERRED PATH
      DECLARE LONG CONSTANT IO$_DISPLAY = 19  ! DISPLAY VOLUME LABEL
      DECLARE LONG CONSTANT IO$_REMSHADMBR = 20  ! REMOVE MEMBER FROM SHADOW SET
      DECLARE LONG CONSTANT IO$_DSE = 21    ! DATA SECURITY ERASE (AND REWIND) 
      DECLARE LONG CONSTANT IO$_REREADN = 22  ! REREAD NEXT 
      DECLARE LONG CONSTANT IO$_DISK_COPY_DATA = 22  ! DISK_COPY_DATA
      DECLARE LONG CONSTANT IO$_MOUNTSHAD = 23  ! CREATE A SHADOW SET
      DECLARE LONG CONSTANT IO$_REREADP = 23  ! REREAD PREVIOUS 
      DECLARE LONG CONSTANT IO$_WHM = 23    ! WRITE HISTORY MANAGEMENT
      DECLARE LONG CONSTANT IO$_AS_SETCHAR = 23  ! ASIAN SET CHARACTERISTICS
      DECLARE LONG CONSTANT IO$_WRITERET = 24  ! WRITE RETRY 
      DECLARE LONG CONSTANT IO$_WRITECHECKH = 24  ! WRITE CHECK HEADER AND DATA 
      DECLARE LONG CONSTANT IO$_AS_SENSECHAR = 24  ! ASIAN SENSE CHARACTERISTICS
      DECLARE LONG CONSTANT IO$_ADDSHADMBR = 25  ! ADD MEMBER TO SHADOW SET
      DECLARE LONG CONSTANT IO$_READPRESET = 25  ! READIN PRESET 
      DECLARE LONG CONSTANT IO$_STARTSPNDL = 25  ! START SPINDLE 
      DECLARE LONG CONSTANT IO$_SETCHAR = 26  ! SET CHARACTERISTICS 
      DECLARE LONG CONSTANT IO$_SENSECHAR = 27  ! SENSE TAPE CHARACTERISTICS 
      DECLARE LONG CONSTANT IO$_WRITEMARK = 28  ! WRITE TAPE MARK 
      DECLARE LONG CONSTANT IO$_COPYMEM = 28  ! COPY MEMORY
      DECLARE LONG CONSTANT IO$_PSXSETCHAR = 28  ! POSIX SET CHARACTERISTICS
      DECLARE LONG CONSTANT IO$_WRTTMKR = 29  ! WRITE TAPE MARK RETRY 
      DECLARE LONG CONSTANT IO$_DIAGNOSE = 29  ! DIAGNOSE 
      DECLARE LONG CONSTANT IO$_SHADMV = 29  ! PREFORM MOUNT VER. ON SHADOW SET
      DECLARE LONG CONSTANT IO$_PSXSENSECHAR = 29  ! POSIX SENSE CHARACTERISTICS
      DECLARE LONG CONSTANT IO$_FORMAT = 30  ! FORMAT 
      DECLARE LONG CONSTANT IO$_CLEAN = 30  ! CLEAN TAPE 
      DECLARE LONG CONSTANT IO$_UPSHAD = 30  ! UPDATE SHADOW SYSDEVICE
      DECLARE LONG CONSTANT IO$_PHYSICAL = 31  ! HIGHEST PHYSICAL I/O FUNCTION CODE 
    ! 
    !  *** START LOGICAL I/O FUNCTION CODES ***
    ! 
      DECLARE LONG CONSTANT IO$_WRITELBLK = 32  ! WRITE LOGICAL BLOCK 
      DECLARE LONG CONSTANT IO$_READLBLK = 33  ! READ LOGICAL BLOCK 
      DECLARE LONG CONSTANT IO$_REWINDOFF = 34  ! REWIND AND SET OFFLINE 
      DECLARE LONG CONSTANT IO$_READRCTL = 34  ! READ RCT SECTOR ZERO
      DECLARE LONG CONSTANT IO$_SETMODE = 35  ! SET MODE 
      DECLARE LONG CONSTANT IO$_REWIND = 36  ! REWIND TAPE 
      DECLARE LONG CONSTANT IO$_SKIPFILE = 37  ! SKIP FILES 
      DECLARE LONG CONSTANT IO$_PSXSETMODE = 37  ! POSIX SET MODE
      DECLARE LONG CONSTANT IO$_SKIPRECORD = 38  ! SKIP RECORDS 
      DECLARE LONG CONSTANT IO$_PSXSENSEMODE = 38  ! POSIX SENSE MODE
      DECLARE LONG CONSTANT IO$_SENSEMODE = 39  ! SENSE TAPE MODE 
      DECLARE LONG CONSTANT IO$_WRITEOF = 40  ! WRITE END OF FILE 
      DECLARE LONG CONSTANT IO$_TTY_PORT_BUFIO = 40  ! BUFFERED I/O TERMINAL PORT FDT ROUTINE
      DECLARE LONG CONSTANT IO$_TTY_PORT = 41  ! TERMINAL PORT FDT ROUTINE
      DECLARE LONG CONSTANT IO$_FREECAP = 41  ! RETURN FREE CAPACITY
      DECLARE LONG CONSTANT IO$_FLUSH = 42  ! FLUSH CONTROLLER CACHE
      DECLARE LONG CONSTANT IO$_AS_SETMODE = 42  ! ASIAN SET MODE
      DECLARE LONG CONSTANT IO$_READLCHUNK = 43  ! READ LARGE LOGICAL BLOCK
      DECLARE LONG CONSTANT IO$_AS_SENSEMODE = 43  ! ASIAN SENSE MODE
      DECLARE LONG CONSTANT IO$_WRITELCHUNK = 44  ! WRITE LARGE LOGICAL BLOCK
      DECLARE LONG CONSTANT IO$_LOGICAL = 47  ! HIGHEST LOGICAL I/O FUNCTION CODE 
    ! 
    !  *** START VIRTUAL I/O FUNCTION CODES
    ! 
    !  NOTE: 
    !  Virtual IO operations to a non-file oriented device require that the process
    !  has READ access priviledges for that device. Specificly, EXE$QIO calls
    !  EXE$CHECK_DEVICE_ACCESS for the following virtual IO function codes to
    !  verify that the the process has read access rights:
    !     READPBLK,READLBLK,READVBLK, READHEAD,READTRACKD,REREADN,REREADP,
    !     READPROMPT,TTYREADALL,TTYREADPALL
      DECLARE LONG CONSTANT IO$_WRITEVBLK = 48  ! WRITE VIRTUAL BLOCK 
      DECLARE LONG CONSTANT IO$_READVBLK = 49  ! READ VIRTUAL BLOCK 
      DECLARE LONG CONSTANT IO$_ACCESS = 50  ! ACCESS FILE 
      DECLARE LONG CONSTANT IO$_PSXWRITEVBLK = 50  ! POSIX WRITE VIRTUAL
      DECLARE LONG CONSTANT IO$_CREATE = 51  ! CREATE FILE 
      DECLARE LONG CONSTANT IO$_DEACCESS = 52  ! DEACCESS FILE 
      DECLARE LONG CONSTANT IO$_PSXREADVBLK = 52  ! POSIX READ VIRTUAL
      DECLARE LONG CONSTANT IO$_DELETE = 53  ! DELETE FILE 
      DECLARE LONG CONSTANT IO$_MODIFY = 54  ! MODIFY FILE 
      DECLARE LONG CONSTANT IO$_NETCONTROL = 54  ! X25 NETWORK CONTROL FUNCTION 
      DECLARE LONG CONSTANT IO$_READPROMPT = 55  ! READ TERMINAL WITH PROMPT 
      DECLARE LONG CONSTANT IO$_SETCLOCK = 55  ! SET CLOCK 
      DECLARE LONG CONSTANT IO$_AUDIO = 55  ! CD-ROM AUDIO
      DECLARE LONG CONSTANT IO$_ACPCONTROL = 56  ! MISCELLANEOUS ACP CONTROL 
      DECLARE LONG CONSTANT IO$_STARTDATA = 56  ! START DATA 
      DECLARE LONG CONSTANT IO$_IOCTLV = 56  ! GENERIC UNIX IOCTL FUNCTIONS
      DECLARE LONG CONSTANT IO$_MANAGE = 56  ! MANAGE DEVICE
      DECLARE LONG CONSTANT IO$_MOUNT = 57  ! MOUNT VOLUME 
      DECLARE LONG CONSTANT IO$_TTYREADALL = 58  !  TERMINAL READ PASSALL 
      DECLARE LONG CONSTANT IO$_DISMOUNT = 58  !  F64 dismount
      DECLARE LONG CONSTANT IO$_TTYREADPALL = 59  !  TERM READ W/PROMPT PASSALL 
      DECLARE LONG CONSTANT IO$_USBATTR = 59  !  USB device attributes
      DECLARE LONG CONSTANT IO$_CONINTREAD = 60  !  Connect to interrupt readonly 
      DECLARE LONG CONSTANT IO$_CONINTWRITE = 61  !  Connect to interrupt with write 
      DECLARE LONG CONSTANT IO$_READDIR = 62  ! READ DIRECTORY CONTENTS
      DECLARE LONG CONSTANT IO$_VIRTUAL = 63  ! HIGHEST VIRTUAL I/O FUNCTION 
    ! 
    !  FUNCTION MODIFIER BIT DEFINITIONS
    ! 
      DECLARE LONG CONSTANT IO$M_FCODE = x'0000003F'
      DECLARE LONG CONSTANT IO$M_FMODIFIERS = x'0000FFC0'
      DECLARE LONG CONSTANT IO$M_INHERLOG = x'00000800'
      DECLARE LONG CONSTANT IO$M_ERASE = x'00000400'
      DECLARE LONG CONSTANT IO$M_EXFUNC = x'00002000'
      DECLARE LONG CONSTANT IO$M_DATACHECK = x'00004000'
      DECLARE LONG CONSTANT IO$M_INHRETRY = x'00008000'
      DECLARE LONG CONSTANT IO$M_SYNCSTS = x'00010000'
      DECLARE LONG CONSTANT IO$M_NOVCACHE = x'00020000'
      DECLARE LONG CONSTANT IO$M_BUFOBJ = x'00040000'
      DECLARE LONG CONSTANT IO$M_TRUSTED = x'00080000'
      DECLARE LONG CONSTANT IO$M_FILE_FLUSH = x'00100000'
      DECLARE LONG CONSTANT IO$M_BARRIER = x'00200000'
      DECLARE LONG CONSTANT IO$M_RAH_HINT = x'00400000'
      DECLARE LONG CONSTANT IO$M_INHSEEK = x'00001000'
      DECLARE LONG CONSTANT IO$M_READ_TO_EOF = x'00200000'
      DECLARE LONG CONSTANT IO$M_REVERSE = x'00000040'
      DECLARE LONG CONSTANT IO$M_NOWAIT = x'00000080'
      DECLARE LONG CONSTANT IO$M_INHEXTGAP = x'00001000'
      DECLARE LONG CONSTANT IO$M_RETENSION = x'00002000'
      DECLARE LONG CONSTANT IO$M_ALLOWFAST = x'00004000'
      DECLARE LONG CONSTANT IO$M_MT3_DENSITY = x'00008000'
      DECLARE LONG CONSTANT IO$M_MSCPMODIFS = x'00000100'
      DECLARE LONG CONSTANT IO$M_SHADOW = x'00000040'
      DECLARE LONG CONSTANT IO$M_LOCATE = x'00000080'
      DECLARE LONG CONSTANT IO$M_MSCP_FORMAT = x'00000040'
      DECLARE LONG CONSTANT IO$M_ALLHOSTS = x'00000040'
      DECLARE LONG CONSTANT IO$M_DISSOLVE = x'00000080'
      DECLARE LONG CONSTANT IO$M_NOCLEANUP = x'00000100'
      DECLARE LONG CONSTANT IO$M_SPINDOWN = x'00000040'
      DECLARE LONG CONSTANT IO$M_EST_COM_PATH = x'00000040'
      DECLARE LONG CONSTANT IO$M_LCL_SRC_UNIT = x'00000080'
      DECLARE LONG CONSTANT IO$M_RTN_COM_PATH = x'00000100'
      DECLARE LONG CONSTANT IO$M_DEALC_ALL = x'00000040'
      DECLARE LONG CONSTANT IO$M_DEALC_HRN = x'00000080'
      DECLARE LONG CONSTANT IO$M_DEALC_ENTLOC = x'00000100'
      DECLARE LONG CONSTANT IO$M_DECR_AFC = x'00000200'
      DECLARE LONG CONSTANT IO$M_READ_ALL = x'00000400'
      DECLARE LONG CONSTANT IO$M_READ_HRN = x'00000800'
      DECLARE LONG CONSTANT IO$M_BREAK_CONN = x'00001000'
      DECLARE LONG CONSTANT IO$M_STEPOVER = x'00000040'
      DECLARE LONG CONSTANT IO$M_COPYOP = x'00000100'
      DECLARE LONG CONSTANT IO$M_EXISTS = x'00000040'
      DECLARE LONG CONSTANT IO$M_CBS = x'00000080'
      DECLARE LONG CONSTANT IO$M_BOOTING = x'00000100'
      DECLARE LONG CONSTANT IO$M_REQ_MINICOPY = x'00000200'
      DECLARE LONG CONSTANT IO$M_OPT_MINICOPY = x'00000400'
      DECLARE LONG CONSTANT IO$M_NOMINICOPY = x'00000800'
      DECLARE LONG CONSTANT IO$M_EXPECT_MOUNT_DONE = x'00002000'
      DECLARE LONG CONSTANT IO$M_VUEX_FC = x'00000200'
      DECLARE LONG CONSTANT IO$M_WRITE_SCB = x'00000200'
      DECLARE LONG CONSTANT IO$M_UPD_SCBLBN = x'00002000'
      DECLARE LONG CONSTANT IO$M_FORCEPATH = x'00000040'
      DECLARE LONG CONSTANT IO$M_PREFERRED_CPU = x'00000080'
      DECLARE LONG CONSTANT IO$M_SYS_ASSIGNABLE = x'00000100'
      DECLARE LONG CONSTANT IO$M_COMMOD = x'00000040'
      DECLARE LONG CONSTANT IO$M_MOVETRACKD = x'00000080'
      DECLARE LONG CONSTANT IO$M_DIAGNOSTIC = x'00000100'
      DECLARE LONG CONSTANT IO$M_SKPSECINH = x'00000200'
      DECLARE LONG CONSTANT IO$M_DELDATA = x'00000040'
      DECLARE LONG CONSTANT IO$M_NOMRSP = x'00000040'
      DECLARE LONG CONSTANT IO$M_SWAP = x'00000100'
      DECLARE LONG CONSTANT IO$M_OPPOSITE = x'00000200'
      DECLARE LONG CONSTANT IO$M_CLSEREXCP = x'00000200'
      DECLARE LONG CONSTANT IO$M_CHUNKDIAG = x'00000040'
      DECLARE LONG CONSTANT IO$M_TBC = x'00000400'
      DECLARE LONG CONSTANT IO$M_ENAREP = x'00000040'
      DECLARE LONG CONSTANT IO$M_ACCESS = x'00000040'
      DECLARE LONG CONSTANT IO$M_CREATE = x'00000080'
      DECLARE LONG CONSTANT IO$M_DELETE = x'00000100'
      DECLARE LONG CONSTANT IO$M_MOUNT = x'00000200'
      DECLARE LONG CONSTANT IO$M_DMOUNT = x'00000400'
      DECLARE LONG CONSTANT IO$M_REMOUNT = x'00000800'
      DECLARE LONG CONSTANT IO$M_MOVEFILE = x'00001000'
      DECLARE LONG CONSTANT IO$M_RWSHELVED = x'00004000'
      DECLARE LONG CONSTANT IO$M_SETDIR = x'00008000'
      DECLARE LONG CONSTANT IO$M_BINARY = x'00000040'
      DECLARE LONG CONSTANT IO$M_PACKED = x'00000080'
      DECLARE LONG CONSTANT IO$M_NOW = x'00000040'
      DECLARE LONG CONSTANT IO$M_STREAM = x'00000080'
      DECLARE LONG CONSTANT IO$M_READERCHECK = x'00000100'
      DECLARE LONG CONSTANT IO$M_WRITERCHECK = x'00000200'
      DECLARE LONG CONSTANT IO$M_NORSWAIT = x'00000400'
      DECLARE LONG CONSTANT IO$M_MB_ROOM_NOTIFY = x'00000040'
      DECLARE LONG CONSTANT IO$M_READATTN = x'00000080'
      DECLARE LONG CONSTANT IO$M_WRTATTN = x'00000100'
      DECLARE LONG CONSTANT IO$M_SETPROT = x'00000200'
      DECLARE LONG CONSTANT IO$M_READERWAIT = x'00000400'
      DECLARE LONG CONSTANT IO$M_WRITERWAIT = x'00000800'
      DECLARE LONG CONSTANT IO$M_NOECHO = x'00000040'
      DECLARE LONG CONSTANT IO$M_TIMED = x'00000080'
      DECLARE LONG CONSTANT IO$M_CVTLOW = x'00000100'
      DECLARE LONG CONSTANT IO$M_NOFILTR = x'00000200'
      DECLARE LONG CONSTANT IO$M_DSABLMBX = x'00000400'
      DECLARE LONG CONSTANT IO$M_PURGE = x'00000800'
      DECLARE LONG CONSTANT IO$M_TRMNOECHO = x'00001000'
      DECLARE LONG CONSTANT IO$M_REFRESH = x'00002000'
      DECLARE LONG CONSTANT IO$M_ESCAPE = x'00004000'
      DECLARE LONG CONSTANT IO$M_EXTEND = x'00008000'
      DECLARE LONG CONSTANT IO$M_CANCTRLO = x'00000040'
      DECLARE LONG CONSTANT IO$M_ENABLMBX = x'00000080'
      DECLARE LONG CONSTANT IO$M_NOFORMAT = x'00000100'
      DECLARE LONG CONSTANT IO$M_BREAKTHRU = x'00000200'
      DECLARE LONG CONSTANT IO$M_NEWLINE = x'00000400'
      DECLARE LONG CONSTANT IO$M_TYPEAHDCNT = x'00000040'
      DECLARE LONG CONSTANT IO$M_MAINT = x'00000040'
      DECLARE LONG CONSTANT IO$M_CTRLYAST = x'00000080'
      DECLARE LONG CONSTANT IO$M_CTRLCAST = x'00000100'
      DECLARE LONG CONSTANT IO$M_HANGUP = x'00000200'
      DECLARE LONG CONSTANT IO$M_OUTBAND = x'00000400'
      DECLARE LONG CONSTANT IO$M_TT_CONNECT = x'00000800'
      DECLARE LONG CONSTANT IO$M_TT_DISCON = x'00001000'
      DECLARE LONG CONSTANT IO$M_TT_PROCESS = x'00002000'
      DECLARE LONG CONSTANT IO$M_BRDCST = x'00004000'
      DECLARE LONG CONSTANT IO$M_LOOP = x'00000080'
      DECLARE LONG CONSTANT IO$M_UNLOOP = x'00000100'
      DECLARE LONG CONSTANT IO$M_LINE_OFF = x'00000200'
      DECLARE LONG CONSTANT IO$M_SET_MODEM = x'00000400'
      DECLARE LONG CONSTANT IO$M_LINE_ON = x'00000800'
      DECLARE LONG CONSTANT IO$M_LOOP_EXT = x'00001000'
      DECLARE LONG CONSTANT IO$M_AUTXOF_ENA = x'00002000'
      DECLARE LONG CONSTANT IO$M_AUTXOF_DIS = x'00004000'
      DECLARE LONG CONSTANT IO$M_INCLUDE = x'00000800'
      DECLARE LONG CONSTANT IO$M_TT_ABORT = x'00001000'
      DECLARE LONG CONSTANT IO$M_POSIXINIT = x'00000040'
      DECLARE LONG CONSTANT IO$M_POSIXFLOW = x'00000080'
      DECLARE LONG CONSTANT IO$M_SET_POSIX = x'00000080'
      DECLARE LONG CONSTANT IO$M_CLEAR_POSIX = x'00000100'
      DECLARE LONG CONSTANT IO$M_SET_TERMIOS = x'00000200'
      DECLARE LONG CONSTANT IO$M_SET_PTC = x'00000400'
      DECLARE LONG CONSTANT IO$M_CLEAR_PTC = x'00000800'
      DECLARE LONG CONSTANT IO$M_FLUSH_TAB = x'00001000'
      DECLARE LONG CONSTANT IO$M_FLUSH_OUTPUT = x'00002000'
      DECLARE LONG CONSTANT IO$M_UPDATE_PTC = x'00004000'
      DECLARE LONG CONSTANT IO$M_OUT_XOFF = x'00000100'
      DECLARE LONG CONSTANT IO$M_OUT_XON = x'00000200'
      DECLARE LONG CONSTANT IO$M_IN_XOFF = x'00000400'
      DECLARE LONG CONSTANT IO$M_IN_XON = x'00000800'
      DECLARE LONG CONSTANT IO$M_O_NONBLOCK = x'00000040'
      DECLARE LONG CONSTANT IO$M_INTERRUPT = x'00000040'
      DECLARE LONG CONSTANT IO$M_MULTIPLE = x'00000080'
      DECLARE LONG CONSTANT IO$M_LOCKBUF = x'00000100'
      DECLARE LONG CONSTANT IO$M_NOBLOCK = x'00000200'
      DECLARE LONG CONSTANT IO$M_ABORT = x'00000100'
      DECLARE LONG CONSTANT IO$M_SYNCH = x'00000200'
      DECLARE LONG CONSTANT IO$M_RESPONSE = x'00000040'
      DECLARE LONG CONSTANT IO$M_STARTUP = x'00000040'
      DECLARE LONG CONSTANT IO$M_SHUTDOWN = x'00000080'
      DECLARE LONG CONSTANT IO$M_ATTNAST = x'00000100'
      DECLARE LONG CONSTANT IO$M_CTRL = x'00000200'
      DECLARE LONG CONSTANT IO$M_SET_MAC = x'00000800'
      DECLARE LONG CONSTANT IO$M_UPDATE_MAP = x'00001000'
      DECLARE LONG CONSTANT IO$M_ROUTE = x'00002000'
      DECLARE LONG CONSTANT IO$M_RD_MEM = x'00000040'
      DECLARE LONG CONSTANT IO$M_RD_MODEM = x'00000080'
      DECLARE LONG CONSTANT IO$M_RD_COUNT = x'00000100'
      DECLARE LONG CONSTANT IO$M_CLR_COUNT = x'00000400'
      DECLARE LONG CONSTANT IO$M_SENSE_MAC = x'00000800'
      DECLARE LONG CONSTANT IO$M_SHOW_MAP = x'00001000'
      DECLARE LONG CONSTANT IO$M_SHOW_ROUTE = x'00002000'
      DECLARE LONG CONSTANT IO$K_SRRUNOUT = 0  !  Send or rcv until cnt runout 
      DECLARE LONG CONSTANT IO$K_PTPBSC = 8192  !  Point to point BSC control 
      DECLARE LONG CONSTANT IO$K_LOOPTEST = 57344  !  Loop test 
    !  X25 driver WRITEBLK function modifier bits.
      DECLARE LONG CONSTANT IO$M_MORE = x'00000040'
      DECLARE LONG CONSTANT IO$M_QUALIFIED = x'00000080'
      DECLARE LONG CONSTANT IO$M_REDIRECT = x'00000040'
      DECLARE LONG CONSTANT IO$M_ACCEPT = x'00000080'
      DECLARE LONG CONSTANT IO$M_SETEVF = x'00000040'
      DECLARE LONG CONSTANT IO$M_WORD = x'00000040'
      DECLARE LONG CONSTANT IO$M_SETFNCT = x'00000200'
      DECLARE LONG CONSTANT IO$M_DATAPATH = x'00000400'
      DECLARE LONG CONSTANT IO$M_CYCLE = x'00001000'
      DECLARE LONG CONSTANT IO$M_RESET = x'00002000'
      DECLARE LONG CONSTANT IO$M_SETCUADR = x'00000100'
      DECLARE LONG CONSTANT IO$M_SETBSIZE = x'00000200'
      DECLARE LONG CONSTANT IO$M_SETPOOLSZ = x'00000400'
      DECLARE LONG CONSTANT IO$M_SETENQCNT = x'00000800'
      DECLARE LONG CONSTANT IO$M_CLEAR = x'00001000'
      DECLARE LONG CONSTANT IO$M_LPBEXT = x'00002000'
      DECLARE LONG CONSTANT IO$M_LPBINT = x'00004000'
      DECLARE LONG CONSTANT IO$M_READCSR = x'00008000'
      DECLARE LONG CONSTANT IO$M_NOCTSWAIT = x'00000040'
      DECLARE LONG CONSTANT IO$M_SLAVLOOP = x'00000080'
      DECLARE LONG CONSTANT IO$M_NODSRWAIT = x'00000100'
      DECLARE LONG CONSTANT IO$M_MAINTLOOP = x'00000200'
      DECLARE LONG CONSTANT IO$M_LASTBLOCK = x'00000400'
      DECLARE LONG CONSTANT IO$M_INTCLOCK = x'00001000'
      DECLARE LONG CONSTANT IO$M_LT_CONNECT = x'00000040'
      DECLARE LONG CONSTANT IO$M_LT_DISCON = x'00000080'
      DECLARE LONG CONSTANT IO$M_LT_READPORT = x'00000100'
      DECLARE LONG CONSTANT IO$M_LT_MAP_PORT = x'00000200'
      DECLARE LONG CONSTANT IO$M_LT_RATING = x'00000400'
      DECLARE LONG CONSTANT IO$M_LT_SOL_INFO = x'00000800'
      DECLARE LONG CONSTANT IO$M_LT_RCV_INFO = x'00001000'
      DECLARE LONG CONSTANT IO$M_LT_SETMODE = x'00002000'
      DECLARE LONG CONSTANT IO$M_LT_SENSEMODE = x'00004000'
      DECLARE LONG CONSTANT IO$M_LT_QUE_CHG_NOTIF = x'00008000'
      DECLARE LONG CONSTANT IO$M_LT_MAP_FILLER = x'00000001'
      DECLARE LONG CONSTANT IO$M_LT_MAP_NODNAM = x'00000002'
      DECLARE LONG CONSTANT IO$M_LT_MAP_PORNAM = x'00000004'
      DECLARE LONG CONSTANT IO$M_LT_MAP_SRVNAM = x'00000008'
      DECLARE LONG CONSTANT IO$M_LT_MAP_LNKNAM = x'00000010'
      DECLARE LONG CONSTANT IO$M_LT_MAP_NETADR = x'00000020'
      DECLARE LONG CONSTANT IO$M_FLUSH = x'00000040'
      DECLARE LONG CONSTANT IO$M_WRITE_BARRIER = x'00000080'
      DECLARE LONG CONSTANT IO$M_MKFILL1 = x'00000040'
      DECLARE LONG CONSTANT IO$M_ALLOWFAST_NEVER = x'00000080'
      DECLARE LONG CONSTANT IO$M_ALLOWFAST_PER_IO = x'00000100'
      DECLARE LONG CONSTANT IO$M_ALLOWFAST_ALWAYS = x'00000200'
      DECLARE LONG CONSTANT IO$M_ADD = x'00000040'
      DECLARE LONG CONSTANT IO$M_IDSTRING = x'00000040'
      DECLARE LONG CONSTANT IO$M_SERIALNUM = x'00000080'
      DECLARE LONG CONSTANT IO$M_BYPASS_VALID_CHK = x'00000080'
      DECLARE LONG CONSTANT IO$S_IODEF = 3
      record IODEF
         variant
    !  Basic I/O function code/modifiers structure
            case
               group IO$R_FCODE_STRUCTURE
                   !  Function Code Field
                   !  Function Modifiers Field
                  WORD FCODE_bits   ! COMMENT ADDED BY SDL - FCODE_bits contains bits FCODE through FMODIFIERS
               end group IO$R_FCODE_STRUCTURE
    !  Function modifiers common to all drivers which do error logging
            case
               group IO$R_ERRLOG_MODIFIERS
                   !  Inhibit error logging
                  WORD fcode_fill_1_bits   ! COMMENT ADDED BY SDL - fcode_fill_1_bits contains bits fcode_fill_1 through FILL_20_
               end group IO$R_ERRLOG_MODIFIERS
    !  General disk and tape function code modifiers
            case
               group IO$R_DISK_TAPE_MODIFIERS
                   !  Erase data
                   !  IO$M_INHERLOG
                   !  func<31:16> are valid
                   !  Write check data after transfer
                   !  Inhibit error retry
    !  the following are only valid if EXFUNC is set
                   !  allow synchronous completion
                   !  do not use VBN cache
                   !  Buffer object I/O
                   !  I/O from trusted component
                   !  Flush file to disk
                   !  Insert a barrier after the write
                   !  Readahead hint (used by XFC)
                  LONG fcode_fill_2_bits   ! COMMENT ADDED BY SDL - fcode_fill_2_bits contains bits fcode_fill_2 through FILL_21_
               end group IO$R_DISK_TAPE_MODIFIERS
    !  General disk function code modifiers
            case
               group IO$R_DISK_MODIFIERS
                   !  Inhibit implied seek on physical functions
                  WORD fcode_fill_3_bits   ! COMMENT ADDED BY SDL - fcode_fill_3_bits contains bits fcode_fill_3 through FILL_22_
               end group IO$R_DISK_MODIFIERS
    !  General disk READ function code modifiers
            case
               group IO$R_DISK_READ_MODIFIERS
                   !  Fill to overlay READ_TO_EOF with BARRIER
    !  the following are only valid if EXFUNC is set
                   !  Reserved for Internal Use only.
                  LONG filler_2a_bits   ! COMMENT ADDED BY SDL - filler_2a_bits contains bits filler_2a through FILL_23_
               end group IO$R_DISK_READ_MODIFIERS
    !  General tape function code modifiers
            case
               group IO$R_TAPE_MODIFIERS
                   !  Reverse operation
                   !  No wait for rewind to complete
                   !  Inhibit extended inter-record gap 
                   !  Traverse the entire tape to uniformly set the tape's tension.
    !   Applies only to IO$_REWIND/REWINDOFF functions
                   !  Allow fast skip by filemarks when enabled
    !   Applies only to IO$_SKIPFILE/SPACEFILE functions
                   !  Density Setmode and Sensemode for MTD enhanced tape drivers.
                  WORD fcode_fill_4_bits   ! COMMENT ADDED BY SDL - fcode_fill_4_bits contains bits fcode_fill_4 through  &
 ! MT3_DENSITY
               end group IO$R_TAPE_MODIFIERS
    !  DU  ? TU, disk ? tape class driver transfer function modifier bits
            case
               group IO$R_DUTU_XFER_MODIFIERS
                   !  Use MSCP modifiers in P5
                  WORD fcode_fill_5_bits   ! COMMENT ADDED BY SDL - fcode_fill_5_bits contains bits fcode_fill_5 through FILL_24_
               end group IO$R_DUTU_XFER_MODIFIERS
            case
               group IO$R_DU_SENSE_MODIFIERS
                   !  Shadowing SENSECHAR
                   !  Shadowing Locate function
                  BYTE fcode_fill_6_bits   ! COMMENT ADDED BY SDL - fcode_fill_6_bits contains bits fcode_fill_6 through LOCATE
               end group IO$R_DU_SENSE_MODIFIERS
            case
               group IO$R_DU_PACKACK_MODIFIERS
                   !  PACKACK media for formatting
                  BYTE fcode_fill_7_bits   ! COMMENT ADDED BY SDL - fcode_fill_7_bits contains bits fcode_fill_7 through FILL_25_
               end group IO$R_DU_PACKACK_MODIFIERS
            case
               group IO$R_DU_AVAIL_MODIFIERS
                   !  Do available as for all class drivers
                   !  Dissolve shadow set
                   !  Normal shadow set cleanup not necessary
                  WORD fcode_fill_8_bits   ! COMMENT ADDED BY SDL - fcode_fill_8_bits contains bits fcode_fill_8 through FILL_26_
               end group IO$R_DU_AVAIL_MODIFIERS
            case
               group IO$R_DU_REMSHAD_MODIFIERS
                   !  Spin down removed member
                  BYTE fcode_fill_9_bits   ! COMMENT ADDED BY SDL - fcode_fill_9_bits contains bits fcode_fill_9 through FILL_27_
               end group IO$R_DU_REMSHAD_MODIFIERS
            case
               group IO$R_DU_DCD_MODIFIERS
                   !  Establish Communication Path
                   !  Local Source Unit
                   !  Retain Communication Path
                  WORD fcode_fill_11_bits   ! COMMENT ADDED BY SDL - fcode_fill_11_bits contains bits fcode_fill_11 through  &
 ! FILL_28_
               end group IO$R_DU_DCD_MODIFIERS
            case
               group IO$R_DU_WHM_MODIFIERS
                   !  Deallocate All
                   !  Deallocate by Host Reference Number
                   !  Deallocate by Entry Locator
                   !  Decrement Allocation Failure Count
                   !  Read All
                   !  Read by Host Reference Number
                   !  Break Connection
                  WORD fcode_fill_12_bits   ! COMMENT ADDED BY SDL - fcode_fill_12_bits contains bits fcode_fill_12 through  &
 ! FILL_29_
               end group IO$R_DU_WHM_MODIFIERS
    !  HBS driver transfer function modifier bits
    !  Make sure that IO$V_SHADOW .ne. IO$V_LOCATE .ne. IO$V_COPYOP
            case
               group IO$R_HBS_COPYSHAD_MODIFIERS
                   !  Stepover SCBLBN.
                   !  Shad Server Cpy Operation
                  WORD fcode_fill_13_bits   ! COMMENT ADDED BY SDL - fcode_fill_13_bits contains bits fcode_fill_13 through  &
 ! FILL_30_
               end group IO$R_HBS_COPYSHAD_MODIFIERS
            case
               group IO$R_HBS_CRESHAD_MODIFIERS
                   !  VU already exists.
                   !  Controller based shadowing.
                   !  Creshad for system disk.
                   !  MINICOPY required
                   !  MINICOPY optional
                   !  NOMINICOPY
                   !  All SSMs on command line sent to HBVS
                  WORD fcode_fill_14_bits   ! COMMENT ADDED BY SDL - fcode_fill_14_bits contains bits fcode_fill_14 through  &
 ! FILL_31_
               end group IO$R_HBS_CRESHAD_MODIFIERS
            case
               group IO$R_HBS_XFER_MODIFIERS
                   !  Exclude Full copy members
                  WORD fcode_fill_15_bits   ! COMMENT ADDED BY SDL - fcode_fill_15_bits contains bits fcode_fill_15 through  &
 ! FILL_32_
               end group IO$R_HBS_XFER_MODIFIERS
            case
               group IO$R_HBS_SCB_MODIFIERS
                   !  Write the SCB
                   !  Update HVBS on new location of the SCB
                  WORD fcode_fill_54_bits   ! COMMENT ADDED BY SDL - fcode_fill_54_bits contains bits fcode_fill_54 through  &
 ! FILL_33_
               end group IO$R_HBS_SCB_MODIFIERS
    !  Function modifier bits for Set Preferred Path. 
            case
               group IO$R_PRFPATH_MODIFIERS
    !  No modifiers set, passes in a preferred path (DUDRIVER)
                   !  Make path change happen (DUDRIVER)
                   !  Set Fast Path CPU affinity of port (port driver)
                   !  system assignable port
                  WORD fcode_fill_10_bits   ! COMMENT ADDED BY SDL - fcode_fill_10_bits contains bits fcode_fill_10 through  &
 ! FILL_34_
               end group IO$R_PRFPATH_MODIFIERS
    !  DR driver function modifier bits.
            case
               group IO$R_DR_MODIFIERS
                   !  Diagnostic command
                   !  Move track descriptor
                   !  Diagnostic function
                   !  Skip sector inhibit
                  WORD fcode_fill_16_bits   ! COMMENT ADDED BY SDL - fcode_fill_16_bits contains bits fcode_fill_16 through  &
 ! FILL_35_
               end group IO$R_DR_MODIFIERS
    !  DY driver function modifier bits.
            case
               group IO$R_DY_MODIFIERS
                   !  Write deleted data mark
                  BYTE fcode_fill_17_bits   ! COMMENT ADDED BY SDL - fcode_fill_17_bits contains bits fcode_fill_17 through  &
 ! FILL_36_
               end group IO$R_DY_MODIFIERS
    !  DD driver (TU58) function modifier bits.
            case
               group IO$R_DD_MODIFIERS
                   !  Do not use MRSP for this operation
                  BYTE fcode_fill_18_bits   ! COMMENT ADDED BY SDL - fcode_fill_18_bits contains bits fcode_fill_18 through  &
 ! FILL_37_
               end group IO$R_DD_MODIFIERS
    !  Magnetic tape I/O function modifier bits for the TS11.
            case
               group IO$R_TS11_MODIFIERS
                   !  Swap byte (TS11)
                   !  Opposite bit for rereads (TS11)
                  WORD fcode_fill_19_bits   ! COMMENT ADDED BY SDL - fcode_fill_19_bits contains bits fcode_fill_19 through  &
 ! FILL_38_
               end group IO$R_TS11_MODIFIERS
    !  TU driver function modifier bits
            case
               group IO$R_TU_MODIFIERS
                   !  Clear serious exception condition
                  WORD fcode_fill_20_bits   ! COMMENT ADDED BY SDL - fcode_fill_20_bits contains bits fcode_fill_20 through  &
 ! FILL_39_
               end group IO$R_TU_MODIFIERS
    !  Tape class driver segmented and large transfer modifier bits
            case
               group IO$R_TU_LG_TRANSFER_MODIFIERS
                   !  Allow diagnostic buffers
                   !  To be continued modifier
                  WORD fcode_fill_21_bits   ! COMMENT ADDED BY SDL - fcode_fill_21_bits contains bits fcode_fill_21 through  &
 ! FILL_40_
               end group IO$R_TU_LG_TRANSFER_MODIFIERS
    !  TUDRIVER SETMODE function modifier bits.
            case
               group IO$R_TU_SETMODE_MODIFIERS
                   !  Enable media quality
                  BYTE fcode_fill_22_bits   ! COMMENT ADDED BY SDL - fcode_fill_22_bits contains bits fcode_fill_22 through  &
 ! FILL_41_
               end group IO$R_TU_SETMODE_MODIFIERS
    !  reporting.
    !  ACP function modifier bits.
            case
               group IO$R_ACP_MODIFIERS
                   !  Access file
                   !  Create file
                   !  Delete file
                   !  Mount volume
                   !  Dismount volume
                   !  Remount volume
                   !  Move a file
                   !  Used for EXFUNC
                   !  Access shelved files
                   !  Set file as a directory
    !  Bit 19 used for TRUSTED
                  WORD fcode_fill_23_bits   ! COMMENT ADDED BY SDL - fcode_fill_23_bits contains bits fcode_fill_23 through SETDIR
               end group IO$R_ACP_MODIFIERS
    !  CR (card reader) driver function modifier bits.
            case
               group IO$R_CR_MODIFIERS
                   !  Binary read
                   !  Packed read
                  BYTE fcode_fill_24_bits   ! COMMENT ADDED BY SDL - fcode_fill_24_bits contains bits fcode_fill_24 through PACKED
               end group IO$R_CR_MODIFIERS
    !  MB (mailbox) driver function modifier bits.
    !  The following modifers are for the QIO READ, WRITE and SENSEMODE
    !  functions.
            case
               group IO$R_MB_MODIFIERS
                   !  Do not wait for operation complete
                   !  Perform stream mode operation (vs. record mode)
                   !  Perform operation if no read channel is assigned to the mailbox.
                   !  Perform operation if no write channel is assigned to the mailbox.
                   !  Do not allow resource waits
    !  Bit 13 used for EXFUNC
    !  Bit 19 used for TRUSTED
                  WORD fcode_fill_25_bits   ! COMMENT ADDED BY SDL - fcode_fill_25_bits contains bits fcode_fill_25 through  &
 ! FILL_42_
               end group IO$R_MB_MODIFIERS
    !  More MB (mailbox) driver function modifier bits.
    !  Mailbox QIO SETMODE function modifiers.
            case
               group IO$R_MB_SETMODE_MODIFIERS
                   !  Notify when some (any) space in the mailbox is available.
                   !  Request ast on waiting reader
                   !  Request ast on waiting writer
                   !  Set volume protection
                   !  Wait for a read channel to be assigned to the mailbox.
                   !  Wait for a write channel to be assigned to the mailbox.
                  WORD fcode_fill_26_bits   ! COMMENT ADDED BY SDL - fcode_fill_26_bits contains bits fcode_fill_26 through  &
 ! FILL_43_
               end group IO$R_MB_SETMODE_MODIFIERS
    !  TT driver READ function modifier bits.
            case
               group IO$R_TT_READ_MODIFIERS
                   !  Noecho
                   !  Timed
                   !  Convert lower case
                   !  No filter
                   !  Disable mailbox
                   !  Purge typeahead
                   !  Terminators are not echoed
                   !  Control-R interrupted read
                   !  Terminate read on escape sequence
                   !  Used by alternate class drivers
                  WORD fcode_fill_27_bits   ! COMMENT ADDED BY SDL - fcode_fill_27_bits contains bits fcode_fill_27 through EXTEND
               end group IO$R_TT_READ_MODIFIERS
    !  TT driver WRITE function modifier bits.
            case
               group IO$R_TT_WRITE_MODIFIERS
                   !  Cancel control O
                   !  Enable mailbox
                   !  Do not format output
                   !  Broadcast I/O
                   !  Output a newline
                  WORD fcode_fill_28_bits   ! COMMENT ADDED BY SDL - fcode_fill_28_bits contains bits fcode_fill_28 through  &
 ! FILL_44_
               end group IO$R_TT_WRITE_MODIFIERS
    !  TT driver SENSEMODE function modifier bits.
            case
               group IO$R_TT_SENSEMODE_MODIFIERS
                   !  Sense typeahead information
                  BYTE fcode_fill_29_bits   ! COMMENT ADDED BY SDL - fcode_fill_29_bits contains bits fcode_fill_29 through  &
 ! reserve_rd_modem
               end group IO$R_TT_SENSEMODE_MODIFIERS
    !  TT driver SETMODE subfunction modifier bits.
            case
               group IO$R_TT_SETMODE_MODIFIERS
                   !  Enable maint sub modifiers
                   !  Set control Y AST
                   !  Set Control C
                   !  Set mode and hang up line
                   !  Set out of band AST
                   !  Connect to detached terminal
                   !  Disconnect detached terminal
                   !  Define controlling process
                   !  Define broadcast mask
                  WORD fcode_fill_30_bits   ! COMMENT ADDED BY SDL - fcode_fill_30_bits contains bits fcode_fill_30 through  &
 ! FILL_45_
               end group IO$R_TT_SETMODE_MODIFIERS
    !  TT driver MAINTIANCE subfunction submodifier bits.
            case
               group IO$R_TT_MAINT_MODIFIERS
                   !  Diagnostic loopback
                   !  Diagnostic reset loopback
                   !  Disable line
                   !  Diagnostic modem control
                   !  Enable line
                   !  Diagnostic external loopback
                   !  Enable auto XOFF
                   !  Disable auto XOFF
                  WORD fcode_fill_31_bits   ! COMMENT ADDED BY SDL - fcode_fill_31_bits contains bits fcode_fill_31 through  &
 ! reserve_int_disable
               end group IO$R_TT_MAINT_MODIFIERS
    !  TT driver out-of-band modifier bits.
            case
               group IO$R_TT_OUTOFBAND_MODIFIERS
                   !  Include character in stream
                   !  Abort current I/O
                  WORD fcode_fill_32_bits   ! COMMENT ADDED BY SDL - fcode_fill_32_bits contains bits fcode_fill_32 through  &
 ! FILL_46_
               end group IO$R_TT_OUTOFBAND_MODIFIERS
    !  Posix terminal driver SETMODE subfunction modifier bits.
            case
               group IO$R_TT_PSXSETMODE_MODIFIERS
                   !  Enable initialization subfunctions
                   !  Enable flow control subfunctions
                  BYTE fcode_fill_33_bits   ! COMMENT ADDED BY SDL - fcode_fill_33_bits contains bits fcode_fill_33 through  &
 ! POSIXFLOW
               end group IO$R_TT_PSXSETMODE_MODIFIERS
    !  Posix terminal driver INIT subfunction submodifier bits.
            case
               group IO$R_TT_POSIXINIT_MODIFIERS
                   !  Set TT3$M_POSIX and set up PTC
                   !  Clear TT3$M_POSIX (opt. delete PTC)
                   !  Set up termios
                   !  Set up all of PTC
                   !  clear PTC
                   !  flush typeahead buffer
                   !  flush outstanding writes
                   !  update PTC
                  WORD fcode_fill_34_bits   ! COMMENT ADDED BY SDL - fcode_fill_34_bits contains bits fcode_fill_34 through  &
 ! FILL_47_
               end group IO$R_TT_POSIXINIT_MODIFIERS
    !  Posix terminal driver FLOW subfunction submodifier bits.
            case
               group IO$R_TT_POSIXFLOW_MODIFIERS
                   !  Simulate output XOFF
                   !  Simulate output XON
                   !  Simulate input XOFF
                   !  Simulate input XON
                  WORD fcode_fill_35_bits   ! COMMENT ADDED BY SDL - fcode_fill_35_bits contains bits fcode_fill_35 through  &
 ! FILL_48_
               end group IO$R_TT_POSIXFLOW_MODIFIERS
    !  Posix terminal driver READ function modifier bits.
            case
               group IO$R_TT_PSXREAD_MODIFIERS
                   !  Nonblock
                  BYTE fcode_fill_36_bits   ! COMMENT ADDED BY SDL - fcode_fill_36_bits contains bits fcode_fill_36 through  &
 ! FILL_49_
               end group IO$R_TT_PSXREAD_MODIFIERS
    !  Network WRITE and READ VIRTUAL function modifier bits.
            case
               group IO$R_NET_WRITE_READ_MODIFIERS
                   !  Interrupt message
                   !  Multiple write/read request 
                   !  Direct I/O request
                   !  Segment message w/o blocking
    !  Bit 13 used for EXFUNC
    !  Bit 19 used for TRUSTED
                  WORD fcode_fill_37_bits   ! COMMENT ADDED BY SDL - fcode_fill_37_bits contains bits fcode_fill_37 through  &
 ! FILL_50_
               end group IO$R_NET_WRITE_READ_MODIFIERS
    !  Network ACCESS/DEACCESS function modifier bits.
            case
               group IO$R_NET_ACCDEA_MODIFIERS
                   !  Disconnect abort/connect reject
                   !  Synchronous disconnect
                  WORD fcode_fill_38_bits   ! COMMENT ADDED BY SDL - fcode_fill_38_bits contains bits fcode_fill_38 through  &
 ! FILL_51_
               end group IO$R_NET_ACCDEA_MODIFIERS
    !  DATALINK driver WRITE subfunction modifier bits.
            case
               group IO$R_DLINK_WRITE_MODIFIERS
                   !  Transmit this packet as a response
                  BYTE fcode_fill_39_bits   ! COMMENT ADDED BY SDL - fcode_fill_39_bits contains bits fcode_fill_39 through  &
 ! FILL_52_
               end group IO$R_DLINK_WRITE_MODIFIERS
    !  DATALINK driver SETMODE subfunction modifier bits. 
            case
               group IO$R_DLINK_SETMODE_MODIFIERS
                   !  Start protocol
                   !  Stop protocol
                   !  Attention AST
                   !  Controller (ie. not station) function
                   !  Set MAC parameters
                   !  Functional Addr Map
                   !  Source Routing Ops
                  WORD fcode_fill_40_bits   ! COMMENT ADDED BY SDL - fcode_fill_40_bits contains bits fcode_fill_40 through  &
 ! FILL_53_
               end group IO$R_DLINK_SETMODE_MODIFIERS
    !  DATALINK driver SENSEMODE subfunction modifier bits.
            case
               group IO$R_DLINK_SENSEMODE_MODIFIERS
                   !  Read device memory
                   !  Read modem status
                   !  Read counters
                   !  Clear counters
                   !  Sense MAC parameters
                   !  Functional Addr Map
                   !  Source Routing Ops
                  WORD fcode_fill_41_bits   ! COMMENT ADDED BY SDL - fcode_fill_41_bits contains bits fcode_fill_41 through  &
 ! FILL_54_
               end group IO$R_DLINK_SENSEMODE_MODIFIERS
            case
               group IO$R_X25_WRITE_MODIFIERS
                   !  More data follows (M-bit)
                   !  Use qualified sub-channel (Q-bit)
                  BYTE fcode_fill_42_bits   ! COMMENT ADDED BY SDL - fcode_fill_42_bits contains bits fcode_fill_42 through  &
 ! QUALIFIED
               end group IO$R_X25_WRITE_MODIFIERS
    !  X25 driver ACCESS function modifier bits.
            case
               group IO$R_X25_ACCESS_MODIFIERS
                   !  Redirect virtual call
                   !  Accept virtual call
                  BYTE fcode_fill_43_bits   ! COMMENT ADDED BY SDL - fcode_fill_43_bits contains bits fcode_fill_43 through ACCEPT
               end group IO$R_X25_ACCESS_MODIFIERS
    !  LPA-11 driver STARTDATA modifier bits.
            case
               group IO$R_LPA_START_MODIFIERS
                   !  Set event flag
                  BYTE fcode_fill_44_bits   ! COMMENT ADDED BY SDL - fcode_fill_44_bits contains bits fcode_fill_44 through  &
 ! FILL_55_
               end group IO$R_LPA_START_MODIFIERS
    !  XA (DR11-W) driver function modifier bits.
            case
               group IO$R_XA_MODIFIERS
                   !  Word (interrupt)/block (DMA) mode specifier
                   !  IO$M_TIMED
                   !  IO$M_ATTNAST, IO$M_DIAGNOSTIC
                   !  Set "FNCT" bits in device CSR
                   !  Change UBA datapath (direct/buffered)
                   !  IO$M_INHERLOG (former def'n for RESET)
                   !  Set "cycle" bit in device CSR
                   !  Device reset specifier
                  WORD fcode_fill_45_bits   ! COMMENT ADDED BY SDL - fcode_fill_45_bits contains bits fcode_fill_45 through  &
 ! FILL_56_
               end group IO$R_XA_MODIFIERS
    !  3271 driver function modifier bits.
            case
               group IO$R_IBM3271_MODIFIERS
                   !  Set a new CU address
                   !  Set a new maximum buffer size
                   !  Set a new pool size
                   !  Set a new ENQ threshold
                   !  Zero status counters
                   !  Loopback is external loopback
                   !  Loopback is internal loopback (DUP11)
                   !  Read CSRs on DUP11
                  WORD fcode_fill_46_bits   ! COMMENT ADDED BY SDL - fcode_fill_46_bits contains bits fcode_fill_46 through  &
 ! READCSR
               end group IO$R_IBM3271_MODIFIERS
    !  XW driver function modifier bits.
            case
               group IO$R_XW_MODIFIERS
                   !  Diagnostic function 
                   !  Diagnostic function 
                   !  Do not wait for DSR (diag) 
                   !  Internal maint loop 
                   !  Last block of message 
                   !  Internal clock 
                  WORD fcode_fill_47_bits   ! COMMENT ADDED BY SDL - fcode_fill_47_bits contains bits fcode_fill_47 through  &
 ! FILL_57_
               end group IO$R_XW_MODIFIERS
    !  LAT driver function modifier bits.
            case
               group IO$R_LT_MODIFIERS
                   !  Solicit connection to remote LAT device
                   !  Disconnect LAT session
                   !  Read LAT device info
                   !  Map application port
                   !  Set service rating
                   !  Request solicit info
                   !  Setup to recive reply
                   !  SETMODE on LTA device
                   !  SENSEMODE on LTA device
                   !  Queue change AST
                  WORD fcode_fill_48_bits   ! COMMENT ADDED BY SDL - fcode_fill_48_bits contains bits fcode_fill_48 through  &
 ! LT_QUE_CHG_NOTIF
               end group IO$R_LT_MODIFIERS
    !  LAT item list definitions for MAP_PORT
            case
               group IO$R_LT_MAPITEM
                   !  Item 0 not used
                   !  Server node name
                   !  Server port name
                   !  Server service name
                   !  Link name
                   !  Server Ethernet Add.
                  BYTE LT_MAP_FILLER_bits   ! COMMENT ADDED BY SDL - LT_MAP_FILLER_bits contains bits LT_MAP_FILLER through  &
 ! FILL_58_
               end group IO$R_LT_MAPITEM
    !  FSDRIVER function modifiers for Dollar.
            case
               group IO$R_FS_MODIFIERS
                   !  Flush writes
                   !  Barrier writes to this point
                  BYTE fcode_fill_49_bits   ! COMMENT ADDED BY SDL - fcode_fill_49_bits contains bits fcode_fill_49 through  &
 ! WRITE_BARRIER
               end group IO$R_FS_MODIFIERS
    !  MKDRIVER function modifiers for SETMODE
            case
               group IO$R_MK_SETMODE_MODIFIERS
                   !  Filler to not coincide with TU modifier (for safety)
                   !  Disable all skip by filemarks
                   !  Enable skip by filemarks with i/o fcn modifier
                   !  Default all IO$_SKIPFILE to use skip by filemarks
                  WORD fcode_fill_50_bits   ! COMMENT ADDED BY SDL - fcode_fill_50_bits contains bits fcode_fill_50 through  &
 ! FILL_59_
               end group IO$R_MK_SETMODE_MODIFIERS
    !  Snapshot-capable disk (SD) driver function modifier bits.
            case
               group IO$R_SD_MODIFIERS
                   !  Add UNIT to an existing pool
                  BYTE fcode_fill_51_bits   ! COMMENT ADDED BY SDL - fcode_fill_51_bits contains bits fcode_fill_51 through  &
 ! FILL_60_
               end group IO$R_SD_MODIFIERS
    !  USB usbattr modifiers
            case
               group IO$R_USB_USBATTR_MODIFIERS
                   !  Request for printer's 1284 device ID string
                   !  Request for printer's serial number (if supported)
                  BYTE fcode_fill_52_bits   ! COMMENT ADDED BY SDL - fcode_fill_52_bits contains bits fcode_fill_52 through  &
 ! SERIALNUM
               end group IO$R_USB_USBATTR_MODIFIERS
    !  Disk-specific PACKACK modifiers 
            case
               group IO$R_DISK_PACKACK_MODIFIERS
                   !  Filler to coincide with MSCP_FORMAT modifier for DU PACKACK
                   !  Send PACKACK to driver even if UCB$M_VALID is set (LCLDSKVALID)
                  BYTE disk_packack_fcode_fill_bits   ! COMMENT ADDED BY SDL - disk_packack_fcode_fill_bits contains bits  &
 ! disk_packack_fcode_fill through BYPASS_VALID_CHK
               end group IO$R_DISK_PACKACK_MODIFIERS
         end variant
      end record IODEF