The tag is present in Lintian version 2.104.319. That is the most recent version we know about.
The machine-readable copyright file uses a field, that used to be defined by the specification, but has been renamed since then.
Please use Format instead of Format-Specification.
Please use Upstream-Contact instead of Contact, Maintainer or Upstream-Maintainer.
Please use Upstream-Name instead of Name.
Please refer to https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/ for details.