VARIABLES READ_WRITE

        CLIC\VARIABLES READ_WRITE ON|OFF

    Input/Output file information (Global).

      IN_FILE          Name if input file
      OUT_FILE         Name of output file
      INBLOC           Block of observation in input file
      IDATA            Address od data section in input observation
      INSEC            Number of sections in header
      INEXT            Next available block in input file
      ONEXT            Next available block in output file
      IXNUM            Index number of current observation in input file
      ISEC [INSEC]     Header sections
      ILEN [INSEC]     Length of header section (words)
      IADD [INSEC]     Addresses of header sections (words)
      IXNEXT           Next available entry in input file index
      OXNEXT           Next available entry in output file index
      CXNEXT           Next available entry in current index
      INWORD           Number of words in current observation
      IDATAL           Length (words) of data section
      MODIFY           (Logical) data is open for modify
      SHARE            (Logical) Output file is shared
      IX_NUM   [ ]     Observation numbers in input file index
      IX_BLOC  [ ]     Blocks numbers of observations in input file
      OX_NUM   [ ]     Observation numbers in output file index
      OX_BLOC  [ ]     Blocks numbers of observations in output file

    The following additional variables are defined by the command FIND:

      FOUND            Number of observations in current index
      CX_NUM   [ ]     Observation numbers in current index
      CX_BLOC  [ ]     Blocks numbers of observations in current index