[latexrefman] node \par

[Vincent Belaïche]

Answering again to myself. Read in node Modes:

@dfn{Paragraph mode} is what @LaTeX{} is in when processing ordinary
text.  It breaks
the input text into lines and breaks the lines into pages.

I would remove the « breaks the lines into pages ». Don't you have to
resort to vertical mode when a page break occur. There is some \vplit
of the current paragraph box at the best possible breakpoint in order
to add it to the outer vertical list in order to keep the page from
overflowing. See TeXByTopic chap 27.

Am I wrong ?

This is rather mysterious to me: doesn't it means that when building a
box through the paragraph line breaking process TeX keeps track of the
potential good break points positions. Then, is there some way to
retrieve explicitely these good positions, or is that hard-coded and
hidden in TeX guts. I am wondering about this after this discussion
https://github.com/olpa/tex/issues/6

  V.

Le lun. 9 août 2021 à 06:24, Vincent Belaïche
<vincent.belaiche at gmail.com> a écrit :
>
> Sorry for my mistake, reading again chap 6 or the TeXByTopic, I found
> that ``horizontal mode'' and ``unrestrcited horizontal mode'' are
> synonyms. Simlarly ``vertical mode'' and `\outer vertical mode''. The
> latters are just as opposed to restrcited horizontal mode, resp. inner
> vertical mode.
>   V.
>
> Le lun. 9 août 2021 à 05:55, Vincent Belaïche
> <vincent.belaiche at gmail.com> a écrit :
> >
> > I came accross this statement (node \par):
> >
> >    In LR mode or a vertical mode the '\par' command does nothing but it
> > terminates paragraph mode, switching LaTeX to vertical mode (*note
> > Modes::).
> >
> > It is hard to understand. I propose to change this as follows
> >
> > In LR mode the \par command does nothing and is ignored.
> > In paragraphe mode the '\par' command terminates paragraph mode,
> > switching LaTeX to vertical mode (*note
> > Modes::).
> >
> > While I am at it, I think we need to mention in the Modes node that
> > (am I wrong?)
> > 1) ``paragraph mode'' is named `ùnrestricted horizontal mode'' in plain TeX,
> > 2) ``horizontal mode'' means either unrestricted horizontal (aka
> > paragraph) or restricted horizontal (aka LR) mode
> > 3) ``vertical mode'' means ``outer vertical'' or `ìnner vertical mode''
> >
> > Comments welcome.
> >   V.