At 2022-12-12T06:15:22+0000, segaloco via TUHS wrote:
> NROFF and TROFF are on the same manual page in 4.1 but split to two
> separate ones in 5.0, perhaps indicating ditroff developments. I
> haven't looked at the differences in the actual pages yet.

If you have scans of these specific pages, I'd be curious to see them.
Thanks to my avocation, my brain's working set has a significant amount
of *roff history in it; maybe I can be useful here.[1]  (The Unix 4.0
documentation with its January 1981 snapshot of newborn
device-independent troff was a fantastic find, in my opinion.)

I can guess what mptx is but I am curious about this "osd" macro
package.  What was it for?

Regards,
Branden

[1] The pages might also help me identify and correct errors in groff
    documentation.