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Date:         Fri, 23 Sep 2011 07:12:44 +0100
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From: Joseph Wright <joseph.wright@MORNINGSTAR2.CO.UK>
Subject: Re: \interlinepenalties
To: LATEX-L@listserv.uni-heidelberg.de
In-Reply-To:  <4E7BAA96.5000506@latex-project.org>
Precedence: list
Status: R

On 22/09/2011 22:37, Frank Mittelbach wrote:
>> One additional note from my experiments is that \interlinepenalties is
>> reset by \par, in the same way \parshape is. I can't see this mentioned
>> anywhere. In contrast, neither \interlinepenalty nor \clubpenalties are!
>> Quite surprising.
> 
> looks like an oversight in the e-TeX manual. But it does make a lot of
> sense to do this (actually very nice because that means you don't have
> to bother about resetting).
> 
> As i said the main use case was preventing pagebreaks for a while
> (couple of lines) after something like a heading, so essentially a
> onetime operation, while culb and widow penaltis are intended for the
> general visual behavior of (i like always at least 1 or tw lines of a
> paragraph on a page if possible) so that this is typically a setting
> that you want to generally apply.
> 
> however that is inconsistent with \interlinepenalty which stays the way
> it is forever.

In the wider context of the galley, the fact that \interlinepenalties is
reset at the end of the paragraph does not help that much. A the \par
may occur inside a group, to reliably 'unset' it you have to \global the
value to 0. With that in mind, it's probably easier to ensure it does
_not_ reset and treat all of the penalties in the same way.
-- 
Joseph Wright