Hi Doug,

At 2024-10-04T21:42:50+0000, Jacobson, Doug W [E CPE] via TUHS wrote:
> Folks:
>
> Long story short, I have a unpublished manuscript that a faculty
> member in my department wrote late 1980's early 2000's.  He did the
> entire thing in troff, eqn, and pic.  The faculty member is still
> alive.  A publisher is interested in the manuscript.  I have all of
> the source files on an old unix machine that still has troff, eqn and
> pic.  It also has groff.  This issue is that the pic commands are
> bracketed by .G1 and .G2 not .PS & .PE.

As others noted, those are the characteristic preprocessor tokens used
by grap(1).

groff(1) says:
     A free implementation of the grap preprocessor, written by Ted
     Faber ⟨faber@lunabase.org⟩, can be found at the grap website
     ⟨http://www.lunabase.org/~faber/Vault/software/grap/⟩.  groff
     supports only this grap.

Distributors often have a package of Faber's grap.  I'm not aware of any
other in circulation.  (Happy to be corrected here.)

Please contact the groff list, groff at gnu dot org, if you have any
problems using it to format these documents and/or to note formatting
discrepancies between Unix troff and groff.  There will likely be some.

I've noted differences between DWB troff and Heirloom troff, so using
the latter does not guarantee identical rendering, and moreover
DWB/System V troff has some bugs/limitations that Heirloom and/or GNU
troffs have fixed, and some of these can affect formatting.

Here's a list from groff's tbl(1) man page, for example.

   GNU tbl enhancements
     In addition to extensions noted above, GNU tbl removes constraints
     endured by users of AT&T tbl.

     •  Region options can be specified in any lettercase.

     •  There is no limit on the number of columns in a table,
        regardless of their classification, nor any limit on the number
        of text blocks.

     •  All table rows are considered when deciding column widths, not
        just those occurring in the first 200 input lines of a region.
        Similarly, table continuation (.T&) tokens are recognized
        outside a region’s first 200 input lines.

     •  Numeric and alphabetic entries may appear in the same column.

     •  Numeric and alphabetic entries may span horizontally.

One can imagine how a 200+-row table could format differently between
DWB/System V and GNU tbl, without either being "wrong".

Regards,
Branden