[Groff] pdfmark XN help

[Anton Shterenlikht]

I discovered pdfmark macro today.
I like it, and would like to use it's
facilities for hyperlinking and automatic
table of contents.

However, pdfmark.pdf included in groff-1.22.2
stops just at this point.
Section 3.1.1.1. "The XN Macro" is empty,
as are all subsequent sections.
The intro says that this document was produced
with groff-1.19.1.

So I wanted to ask, is pdfmark still maintained,
or is it abandoned?
Or perhaps there is an updated pdfmark.pdf
somewhere?
XN is defined in spdf.tmac,
but I lack the skills to understand it.

Please help/advise

Thanks

Anton