Re: [groff] [UTROFF] references, summary, index

[Doug McIlroy]

I am still puzzled about paragraph-at-a-time typesetting in groff.

How does Utroff deal with even simple changes of line length, e.g. for
flowing text around an image as in the following trivial example.
A robust version that allows for intervening page or paragraph
breaks would pose even more difficulty.

        .wh \n[nl]+3 `in +1.5i
        .wh \n[nl]+3+2i `in -1.5i
        Paragraph text here ...

The conundrum is that the placement of the picture is defined
by line breaks, but with paragraphwise justification, the
line breaks depend on where the picture is.

Unjustified text is becoming quite common these days, presumably
because the added shape of text helps the eye maintain vertical
sync. I personally prefer it.

On unjustified text, fmt (which uses an algorithm purported to be
like Knuth-Plass) does a worse job than nroff. Its scoring method
has a significant chance of making a paragraph less uniform
than nroff--perhaps because it isn't sufficiently "like
Knuth-Plass". But it also has a habit that seems intrinsic
to paragraphwise justification: each paragraph appears to
have its own distinct line length. How does Utroff address
this pitfall?

Doug