The tag is present in Lintian version 2.104.328. That is the most recent version we know about.
debian/control file contains an XC-Package-Type field.
As of dpkg-dev 1.15.7, the dpkg development utilities recognize
Package-Type as an official field name and do not add it to binary
packages (the previous concern with the dpkg-dev-supported Package-Type
field). XC-Package-Type should generally now be replaced with