> the former macro isn't behaving as advertised.
It is behaving as documented, you want a version that does
\ensuremath{\pm} but this is way off topic for xsl list.

> I also noticed a file texmf/tex/latex/misc/isolatin1.sty
don't use that with latex.


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list