The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
A list of files in the machine-readable copyright format appears to be separated by commas. The file list should be whitespace separated instead.
Please note this tag is only emitted once per checked copyright file.
Refer to https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/ for details.