Re: Differences in `ne` and `bp` line-breaking behavior

[G. Branden Robinson]

Hi Doug,

At 2024-12-04T12:00:52-0500, Douglas McIlroy wrote:
> I don't see this wording as an improvement:
> 
> >   .ne d    Advance drawing position to the next vertical
> >            position trap and spring the trap, if it is
> >            nearer than distance d (default scaling unit v).
> 
> The proposal uses nonstandard terminology ("drawing position"),

As implied by onf's reply to you, the fault for this term can be laid at
my doorstep.  Here's the context of its introduction.

---snip---
5.2 Page Geometry
=================

...

   While the formatter (and, later, output driver) is processing a page,
it keeps track of its "drawing position", which is the location at which
the next glyph will be written, from which the next motion will be
measured, or where a geometric object will commence rendering.
Notionally, glyphs are drawn from the text baseline upward and to the
right.(1)  (*note Page Geometry-Footnote-1::) A glyph therefore "starts"
at its bottom-left corner.  The formatter's origin is thus one vee below
the page top, preventing a glyph from lying partially or wholly off the
page.
---end snip---

Parallel language is in subsection "Page geometry" of roff(7).

> Also .ne is effective in the absence of traps, a fact that groff(7)
> misses, too.

"Implicit page trap" is another term I felt compelled to coin, because
otherwise I couldn't explain how anyone could have a multi-page troff
document _without_ invoking the `bp` request, and onf quoted my
presentation of it accurately.

Speaking of (non)standardization, today brought a strange coincidence.

https://austingroupbugs.net/view.php?id=1883

Regards,
Branden

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