FILE

        TASK\FILE "Prompt text" Name = [Filename] [/OLD] [/NEW]

    Define  the  parameter Name of Character type, and assign it a filename.
    Otherwise, prompt with the text for a content.  In Windows mode,  launch
    a file browser to get the filename.

    NOT  IMPLEMENTED:  if option /OLD (resp. /NEW) is present, the file must
    (resp. must not) already exist.