Boolean test in xsl:if

How could this come back True:

<xsl:if test="$var1 &lt; $var2">

And this be False?

<xsl:if test="$var1 - $var2 &lt; 0">

I'm using Resin.  Also happens with <xsl:choose>

Actually, when I tried <xsl:if test="21 &lt; 20"> this was also True.  Am I
missing something?  It does not happen on Xalan, but before I chalked it up
to a bug (that I can at least work around, evidently), I thought I'd see if
I'm missing something obvious.

Thanks,

- Mark

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