Structure of nroff printer drivers

[M11816 at MBVM.mitre.org]

I have two maverick printers (DEC LN03 and Qume Sprint) that I would
like to build /usr/lib/term/* NROFF printer driver tables for. Unlike
other versions of UNIX I have used, the structure for these tables
doesn't seem to be documented. I can find familiar looking strings in
the tables that come with 3.51 but they aren't exactly what the
documented STRUCTs in other UNIX versions prescribe.  Anybody know what
the official structures are and whether there are any surprises in
building the tables?  Thanks in advance.