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

[onf]

Reading your message for at least the third time, I conclude that:

On Mon Dec 2, 2024 at 3:26 AM CET, G. Branden Robinson wrote:
> [...]
> >   $ nroff << EOF | sed -E 's/^/./'
> >   .pl 3
> >   .fi
> >   One two three
> >   four five six
> >   'bp
> >   seven eight nine
> >   .br
> >   eleven twelve.
> >   EOF
> > output:
> >   .
> >   .
> >   .
> >   .One two three four five six seven eight nine
> >   .eleven twelve.
> >   .
> > 
> > It's obvious here that 'bp breaks page IMMEDIATELY, not when the .br
>
> Eh?
>
> If it broke the page "IMMEDIATELY", you'd get this:
>
>     One two three four five six
> <page break>
>     seven eight nine eleven twelve.

page break = end line, end page

> [...]
> > It's obvious here that 'bp breaks page IMMEDIATELY,
>
> It doesn't.  It _schedules_ (or enqueues) a page break to occur when the
> next (line) break does, causing the line to be set on the next page.

page break = end page

Please correct me if I'm wrong.

Consulting the web, a 'page break' is variously defined as one of:
  start of a new page
  end of a page
  end a page without filling it with text
  end the current page and begin the next

I think the core of the problem lies in the fact that neither of us
distinguished between a soft and hard page break.

I realize my usage hasn't been entirely consistent either, because
a "hard" page break (.bp) implies a line break to me, and so I
sometimes expected 'page break' to imply a line break and sometimes
not, just as you seem to have.

Consulting the web, a 'hard page break' is defined as variations on:
  The hard page break puts the next word at the top of a new page.

Whereas a soft page break is described as:
   "Soft" page breaks are created by word processing and report
   programs based on the current page length setting.

When I read "break page" in the manpage, I expect it to mean a hard
page break, because a soft page break is automatically inserted when
the text exceeds page length. I expect .ne to emit a hard page break
for the same reason.

Hopefully we are on the same page now. (Pun somewhat intended.)

~ onf