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<DIV><FONT face="Arial Unicode MS" size=2>Dear All</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>Since starting to use (plain) XeTeX
I've noticed something strange with the paragraphing/line-breaking mechanism
which has never happened during the ten years or so during which I have
used traditional TeX. It is cropping up in the fourth issue of a
periodical that I have set with XeTeX, so I'm pretty sure that it's not a random
fluke.</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>(1) I sometimes get an overfull rule
(i.e. rectangular box) at the right-hand side which will disappear when I
either (a) attach the word causing the problem to the next word with ~, forcing
it over (I sometimes have to put the word in an \hbox{} as well); or (b) when I
increase the line-count by giving \looseness1 for the paragraph. In the
past, plain TeX would always make such decisions for itself and never generate
an overfull rule when it could find a way to justify the paragraph without doing
so. This happens most frequently in the reviews section of the periodical,
where \looseness is set to -1 by default to save as much space as
possible: but until I started to use XeTeX, it was always the case that if
the paragraph could not lose a line, then the negative looseness was ignored and
the paragraph was set successfully with normal looseness (i.e. \looseness
= 0). It was never (I think) the case that a tight looseness which
generated an overfull box would get through and need manual intervention
from me. So has something altered in the way XeTeX is handling the
line-breaks, giving priority to the looseness command even at the expense of
generating an overfull rule, and even when zero looseness would cause that error
to disappear?</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>(2) This is even more puzzling (and
more of an nuisance). For the purpose of sending contributors proofs
of their reviews I start each review on a new page so that they don't also
receive the tops and tails of adjacent reviews, but while initially typesetting
I have the reviews running on consecutively, as they will <FONT
face="Arial Unicode MS" size=2></FONT>do in the final published version.
There is a switch at the end of each review which generates a \vfill \eject
when \ifseparatereviews is true, otherwise it just produces a \vskip: there is
no other difference. Yet I sometimes get overfull rules showing up (at
random points) when the reviews are separated out, even though the same
paragraph typeset without error while the reviews were set to run on
continuously. The problem almost (but not entirely) disappears if
I double the \hfuzz when the \ifseparatereviews switch is true, but that is
no more than a quick fix to prevent authors receiving proofs with worrying blobs
at the right-hand side. This seems incomprehensible, but as it has
happened with four out of four periodical issues I can't be imagining it - and
the commands are precisely the same as the ones I used when the periodical was
typeset using traditional plain TeX, with no new parameters such as alteration
to \spaceskip or anything else that might cause this to happen.</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>(1) and (2) seem likely to be part of
the same problem (though not necessarily so). Any ideas, or at least
insight into what XeTeX is doing that old plain TeX didn't?</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>Thanks</FONT></DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2></FONT> </DIV>
<DIV><FONT face="Arial Unicode MS" size=2>John</FONT></DIV>
<DIV> </DIV>
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