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<title>UK TeX FAQ -- question label checksum</title>
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<h3>Checksum mismatch in font</h3>
<p/>When Metafont generates a font it includes a checksum in the font bitmap
file, and in the font metrics file (TFM).  (La)TeX includes
the checksum from the TFM file in the DVI file.
<p/>When <i>dvips</i> (or other DVI drivers) process a
DVI file, they compare checksums in the DVI file to
those in the bitmap fonts being used for character images.  If the
checksums don&rsquo;t match, it means the font metric file used by (La)TeX
was not generated from the same Metafont program that generated the
font.
<p/>This commonly occurs when you&rsquo;re processing someone else&rsquo;s DVI
file.
<p/>The fonts on your system may also be at fault: possibilities are that
the new TFM was not installed, or installed in a path after an
old TFM file, or that you have a personal cache of bitmaps from
an old version of the font.
<p/>In any case, look at the output &ndash; the chances are that it&rsquo;s perfectly
OK, since metrics tend not to change, even when the bitmaps are
improved.  (Indeed, many font designers &mdash; Knuth included &mdash;
maintain the metrics come what may.)
<p/>If the output <em>does</em> look bad, your only chance is to regenerate
things from scratch.  Options include: flushing your bitmap cache,
rebuild the TFM file locally, and so on.
<p/><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=checksum">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=checksum</a>
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