User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2 I have been looking at MathML with parallel markup (see http://www.w3.org/TR/MathML3/chapter5.html#mixing.parallel) and I have a problem with spurious whitespace. In the example file there is has no space between the <m:math> element and the dot. BUT in my firefox there is a clearly visible space of (subjectively) about 2em. This seems to be generated by the parallel markup: if I delete the <m:semantics> and <m:annotation-xml> elements, then the space disappears. So this seems to be an error in firefox. I can hardly believe that I am the only one who has tried something like this. This is especially bad, since whitespace after formulae is considered a newbie error among mathematicians. BTW, IE with Mathplayer gets this right. Reproducible: Always

Can also reproduce this also on Linux and actually found the issue with the parsing. The <m:semantics> tag introduces the extra space after the end of the formula. The attachment is the same as the provided file, only with a <m:semantics> wrapper around the content MathML and the whitespace appears. So, this leads me to think that the bug relies in how the <m:semantics> tag is treated.

Fixed by the patch of bug 556767.