SUBROUTINE   LOAD_COMMON_BLOCK ( IO_UNIT, FILE_NAME, STATUS )
C----------------------------------------------------------------------
C-
C-   Purpose and Methods : Initialize the common block for subsequent direct
C-                         access or use of library routines.
C-
C-                         This subroutine opens the Lookup Management File,
C-                         initializes the common block from the file, and
C-                         then closes the file.
C-
C-   Inputs  :
C-      IO_UNIT            Is the logical unit number to use for input file.
C-
C-      FILE_NAME          Is the name of the Lookup System Management file
C-                         to use as input in filling the common block.
C-
C-   Outputs :
C-      STATUS             Is the number of messages generated. For error
C-                         status, check the common block variable
C-                         LSM_ERROR_SEVERITY
C-
C-   filled common block : LEVEL1_LOOKUP.
C-
C-   Controls: None
C-
C-   Comments :
C-
C-                         The most useful status for the Lookup System Manager
C-                         Program is the common block variable
C-                         LSM_ERROR_SEVERITY.
C-
C-   Defined 21-FEB-1990 MICHIGAN STATE UNIVERSTITY, TRIGGER CONTROL SOFTWARE
C-   Created   6-JUN-1990   MICHIGAN STATE UNIVERSITY, TRIGGER CONTROL SOFTWARE
C-   Updated  10-AUG-1990   MICHIGAN STATE UNIVERSITY, TRIGGER CONTROL SOFTWARE
C-   Updated  22-AUG-1990   MICHIGAN STATE UNIVERSITY, TRIGGER CONTROL SOFTWARE
C-
C----------------------------------------------------------------------
      IMPLICIT NONE
C----------------------------------------------------------------------
C
C       global declarations
C
      INCLUDE  'LSMP$SOURCE:PARSE_TOKENS.PARAMS'
      INCLUDE  'LSMP$SOURCE:PARSE_TOKENS.INC'
C
C
C       Argument declarations
C
      INTEGER IO_UNIT
      CHARACTER*(*) FILE_NAME
      INTEGER STATUS
C
C       Local variables
C
      LOGICAL OK, ERROR
C
C
      LSM_ERROR_SEVERITY = ERROR_NONE
      LSM_ERROR_LINE = 0
      LSM_ERROR_CODE = 0
      LSM_IOSTAT = 0
      MESSAGE_COUNT = 0
      CALL INIT_COMMON_BLOCK()
      CALL INIT_NEXT_WORD()
      CALL INIT_WIDTHS()
      CALL INIT_STRINGS()
      CALL INIT_CLASSES()
      CALL INIT_MESSAGES()
C
C       open the Lookup System Management File
      CALL D0OPEN( IO_UNIT, FILE_NAME, 'IF', OK)
C
      IF (VERBOSE) THEN
        IF ( OK .EQV. .TRUE. ) THEN
          WRITE (6,*) 'Lookup description file opened.'
        ELSE
          WRITE (6,*) 'Error opening description file.'
        ENDIF
      ENDIF
      IF ( OK .EQV. .TRUE. ) THEN
C
        CALL DISPATCH( IO_UNIT, ERROR )
        CALL CLOSE_MGMT_FILE( IO_UNIT )
        IF (DIAGNOSTICS) CALL CHECK_COMMON_BLOCK()
        CALL DERIVED_QUANTITIES()
      ELSE
        CALL MESSAGE_OUT(MES_OPEN_FAILED , 0, ' ')
      ENDIF
C
      STATUS = MESSAGE_COUNT
C
  999 CONTINUE
      END