Valid on Alpha and Integrity server systems only.

    Generates a string that is suitable to be a file name and is
    guaranteed to be unique across the cluster. Unique file names can
    be useful when creating temporary files.  The string returned
    is alphanumeric and may be used as a file name, logical name,
    or DCL symbol name or value with no reserved character issues.

    The F$UNIQUE function has no arguments, but must be followed by a
    blank pair of parentheses.

    Format

      F$UNIQUE()