The tag is present in Lintian version 2.104.234. That is the most recent version we know about.
This package provides at least one file in
which is intended for detached debugging symbols, but the package name
does not end in "-dbg". Detached debugging symbols should be put into a
separate package, Priority: extra, with a package name ending in "-dbg".
Refer to Debian Developer's Reference section 6.7.9 for details.