Thanks Branden and Norwid for the replies.

I hope to be able to revise my adjustments in the beginning of January and will 
post them here.

Kind regards,

Hans

On December 7, 2025 8:53:46 AM GMT+01:00, "G. Branden Robinson" 
<[email protected]> wrote:
>Hi Norwid,
>
>At 2025-11-12T19:38:49+0100, Norwid Behrnd wrote:
>> While browsing though the examples of `chem` Linux Debian provides in
>> path `/usr/share/doc/groff-base/examples/chem`, I noticed a chemical
>> error in file `ATP.chem`, i.e., a missing nitrogen atom.
>
>Well, _that's_ not good...
>
>> This lead to an observation of maybe a second one.
>> 
>> Given Hans' preliminary modifications of `chem` as shared in his email
>> by September 27th, I used the archived he included for a gradual
>> correction / modification of `ATP.chem` in question.  To best of my
>> knowledge, the new bond types proposed were not yet added to the
>> commit history of groff.  This is the reason why this email includes a
>> .zip archive the most relevant files to ease a replication by Hans and
>> other volunteers interested.
>
>Correct, nothing along those lines has been committed yet.  When there
>is consensus regarding a code change to groff, two good procedures for
>people who aren't already committers are (1) mail this list with a
>"[PATCH]" annotation in the subject line; or (2) file a Savannah ticket.
>
>https://savannah.gnu.org/bugs/?group=groff
>
>Sometimes a patch proposal is a good idea even for people who _are_
>committers; observe
>
>https://lists.gnu.org/archive/html/groff/2025-11/msg00003.html
>
>...for example.
>
>> Revisions `atp_r03.chem` and above build on Hans' work (->
>> `Chem.pdf`), hence can not be rendered by the current original `chem`
>> preprocessor (-> `ChemO.pdf`).
>> 
>> @Hans, and interested volunteers: Contrary to the examples compiled by
>> Hans, I observe the proposed new bond types `wedge` and `rwedge` work
>> will within a plain cycle, e.g. `ring5` in code block `atp_r03.chem:`.
>> They however appear to be incompatible with an additional explicit
>> definition of a non-C atom (`put O at 1`, block `atp_r04.chem:`
>> because `chem` now interprets them to belong to keyword `double`.
>> 
>> This might represent a bug in Hans' proposition, separate from the
>> missing nitrogen atom in `ATP.chem` (last commit by 11 Novembre 2020).
>
>The foregoing sounds like solid peer review of Hans's proposal.  We
>don't want to catch only mere typos, but design errors.
>
>> @Branden:  My preference is to address the bond issue in `ATP.chem`
>> first,
>
>I agree.  However, the ZIP file you attached appears to contain only
>additional ATP molecule examples, not a patch, properly considered, to
>the existing one.
>
>I propose the following minimal correction of the existing file:
>
>$ git diff
>diff --git a/contrib/chem/examples/atp.chem b/contrib/chem/examples/atp.chem
>index 738c4da3c..d36c5175d 100644
>--- a/contrib/chem/examples/atp.chem
>+++ b/contrib/chem/examples/atp.chem
>@@ -25,8 +25,11 @@ atp.chem:
> # The GPL2 license text is available in the internet at
> # <http://www.gnu.org/licenses/gpl-2.0.html>.
>
>-R1:    ring5 pointing left double 1,2 3,4 put N at 2 put N at 5
>-B:     benzene put N at 2 with .V6 at R1.V3 with .V5 at R1.V4
>+# corrected missing nitrogen atom, Norwid Behrnd 2025-11-11
>+
>+R1:    ring5 pointing left double 1,2 put N at 2 put N at 5
>+B:     benzene put N at 2 put N at 4 double 1,2 3,4 5,6 \
>+               with .V6 at R1.V3 with .V5 at R1.V4
>        bond up ; NH2
>        backbond 170 length .7 from R1.V5
> R2:    ring5 pointing down with .V2 put O at 1
>
>I reduced the change to not omit the "Thiele ring".  I am unfamiliar
>with this term and the English Wikipedia is no help; I assume you refer
>to what my limited education calls a "benzene ring".
>
>I attach screenshots of the PostScript generated by the unpatched and
>patched files.  To my minimally trained eye your corrected version
>looks, uh, topologically equivalent to Wikipedia's info box for ATP.
>
>But please correct me if I am mistaken.
>
>> subsequently consider filing a PR with a revised `ATP.chem` to the git
>> history of groff.
>
>More or less.  We don't use a GitHub/GitLab-style system, so our "pull
>requests" are either Savannah tickets or emails to this list, as noted
>above.
>
>Thanks for giving your attention to this under-appreciated component of
>groff!
>
>Regards,
>Branden

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