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From: eijkhout@s41.csrd.uiuc.edu (Victor Eijkhout)
Newsgroups: comp.text.tex
Subject: Re: error in LaTeX's \paragraph command
Keywords: latex, paragraph
Message-ID: <1991Jan14.180927.14720@csrd.uiuc.edu>
Date: 14 Jan 91 18:09:27 GMT
References: <9562@mirsa.inria.fr> <1991Jan14.000029.3377@csis.dit.csiro.au> <JTKOHL.91Jan14103220@quicksilver.MIT.EDU>
Sender: news@csrd.uiuc.edu (news)
Organization: UIUC Center for Supercomputing Research and Development
Lines: 34

jtkohl@MIT.EDU (John T Kohl) writes:

>In article <1991Jan14.000029.3377@csis.dit.csiro.au> ken@csis.dit.csiro.au (Ken Yap) writes:

>> >When the "\paragraph" is followed by a word beginning with "plus" or "Plus",
>> >eg. 
>> >    \paragraph{title of the paragraph}
>> >    Plusieurs ...
>> >LaTeX will report the error as follows:
>> > ...
>> >I think it may be a bug in LaTeX.

>> Yes, it's a bug. ... The fix is for macro package writers to be
>> careful to put \relax after such commands.

>What I don't understand is why putting \relax after the \paragraph{foo}
>fails to fix the problem. 

Very well observed. Took me a second to figure this one out:
the crux is that it only goes wrong with \paragraph, not with \section,
because only with the former the heading is embedded in the text.
The \hskip command that accidentally absorbs the 'plus'
in only inserted by the \everypar, and that happens at the moment
the 'P' is encountered.

So in 
\paragraph{ .. }
\relax
Plus...
The \relax is glossed over: the net effect is still
\hskip ... Plus
Remedy: put \leavevmode in front of 'Plus...'.

Victor.