@whynothugo @navi Can .Xr be used in man(7) pages?
Because as far as I know it's an mdoc(7) exclusive and I don't think you can mix two sets of troff macros.
(Although mdoc(7) is a bit more standalone since mandoc, but groff as used by manpagers like man-db on most Linuxes also supports mdoc(7) so still somewhat a set of troff macros)