Re: RS/RE and (relative) inset (was: RS/RE and paragraphing macros)

[G. Branden Robinson]

Hi Alex,

At 2023-02-21T11:13:00+0100, Alex Colomar wrote:
> On 2/21/23 01:18, G. Branden Robinson wrote:
> > I have tried to write the groff_man(7) page accurately and concisely
> > for experienced *roff macro package users, and groff_man_style(7) in
> > a more tutorial and accommodating way for newcomers.
> 
> I'll read them some day :-)

I dare say you'll get a more coherent explanation out of language I have
labored over and revised many times than that which I dash off over
email.

(Or perhaps not.  :-O  You then proceeded to address
groff_man_style(7)'s content in your next reply, quoted below.)

> >      The indentation amount exhibited by ordinary paragraphs set
> >      with .P (and its synonyms) not within an .RS/.RE relative
> >      inset, and the default used when .IP, .RS, .TP, and the
> >      deprecated .HP are not given an indentation argument, is 7.2n
> >      for typesetting devices and 7n for terminal devices (but see
> >      the -rIN option).
> 
> This sentence is very unclear to me.  The indentation amount of .P is 0.
> What's this intending to say?

It's intending to say that people may have noticed that...

.P
Foobar.

       Foobar.

...is not set at the leftmost character cell (strictly, "page offset" to
the formatter).  This does appear to be a lingering failure to use the
term "left margin".

> >      Headers, footers (both set with .TH), and section headings
> >      (.SH) are set at the left margin, and subsection headings (.SS)
> >      indented from it by 3n (but see the -rSN option).
> 
> Hmmm, this seems like absolute movement of the left margin.  Isn't it?

Yes it is.

> Although you can consider these are resetting all previous inset and
> indentation, which effectively results in absolute setting to 0 and
> 3n.

Right.  Unless you are Albert Cahalan, in man(7) pages, only the
headers/footers and section headings are set at a horizontal position of
zero.

> >      HTML output devices ignore indentation.
> 
> Do they ignore left margin, indentation or both?  You could be more
> precise.

Good point!  It might be safer to say that they HTML output ignores
inset and indentation _parameters_.

> The example above lacks something.  You could show how when an IP is
> followed by a lot of stuff inset with RS, followed by RE and IP, the
> IP after RE has the same indentation as specified by the first IP,
> even if in the middle there were Ps.

Okay.  I think I may want to create a second example for that case.
But...

> >      o .RS doesn't indent relative to my indented paragraph.
> >          The .RS macro sets the left margin; that is, the position
> >          at which an ordinary paragraph (.P and its synonyms) will
> >          be set.  .IP, .TP, and the deprecated .HP use the same
> >          default indentation.  If not given an argument, .RS moves
> >          the left margin by this same amount.  To create an inset
> >          relative to an indented paragraph,

...maybe I shoud add "(.IP)" here...

> >          call .RS repeatedly until an acceptable indentation is
> >          achieved, or give .RS an indentation argument that is at
> >          least as much as the paragraph's indentation amount
> >          relative to an adjacent .P paragraph.  See subsection
> >          "Horizontal and vertical spacing" above for the values.
> > 
> >          Another approach you can use with tagged paragraphs

...maybe I should add "(.TP)" here...

> >          is to place an .RS call immediately after the paragraph
> >          tag; this will also force a break regardless of the width
> >          of the tag, which some authors prefer.  Follow-up
> >          paragraphs under the tag can then be set with .P instead of
> >          .IP.  Remember to use .RE to end the indented region before
> >          starting the next tagged paragraph (at the appropriate
> >          nesting level).

...since this item squarely addresses the point you just raised, I'm
curious to hear whether you find it illuminating.

Regards,
Branden

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