VMS Help Lexicals, F$TYPE, Examples  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    1.$ NUM = "52"
      $ TYPE = F$TYPE(NUM)
      $ SHOW SYMBOL TYPE
        TYPE = "INTEGER"

      This example uses the F$TYPE function to determine the data
      type of the symbol NUM. NUM is equated to the character
      string "52". Because the characters in the string form a valid
      integer, the F$TYPE function returns the string INTEGER.

    2.$ NUM = 52
      $ TYPE = F$TYPE(NUM)
      $ SHOW SYMBOL TYPE
        TYPE = "INTEGER"

      In this example, the symbol NUM is equated to the integer 52.
      The F$TYPE function shows that the symbol has an integer data
      type.

    3.$ CHAR = "FIVE"
      $ TYPE = F$TYPE(CHAR)
      $ SHOW SYMBOL TYPE
        TYPE = "STRING"

      In this example, the symbol CHAR is equated to the character
      string FIVE. Because the characters in this string do not form
      a valid integer, the F$TYPE function shows that the symbol has
      a string value.

    4.$ x = F$CONTEXT("PROCESS",CTX,"USERNAME","SMITH")
      $ TYPE = F$TYPE(CTX)
      $ SHOW SYMBOL TYPE
        TYPE = "PROCESS_CONTEXT"
      $ x = F$CONTEXT("PROCESS",CTX,"CANCEL")
      $ TYPE = F$TYPE(CTX)
      $ SHOW SYMBOL TYPE
        TYPE = ""

      In this example, the F$TYPE function returns the string
      PROCESS_CONTEXT because the symbol has been produced by a call
      to the F$CONTEXT function with a context type of PROCESS. The
      symbol returns this type until F$CONTEXT is called with the
      symbol and the selection-item argument value CANCEL.