Each specified filename can identify either a disk file or a system device. File descriptions must have the following format:

      +-device:-+ +--.-----------.---filename--.------.--+
                     +-pathname\-+             +-.ext-+

Each filename or directory name can consist of up to 254 characters and contain any number of periods (.).

This COBOL system regards any text following the final period as an extension (or a trailing period as a space extension) and removes it when creating its own names. Therefore, if you do use multiple periods for a source filename, you must specify an extension.