FILENAME                     file name

    Equal  to  string  value  of  current  filename,  including  any   path
    specified.  If the value of  this variable is be set to  another value,
    QTAwk attempts to open a file with a name equal to the string value  of
    the new  value.   If a  file does  not exist,  a file  opening error is
    issued.  If the file does exist, it becomes the current input file.