(Follow-up from bug 324472 comment 10) Some MathML atoms in nsGkAtomList.h and nsTreeSanitizer.cpp seem to be unused (and wrongly mentioned in the MathML3 element index). We should probably remove them. To be under consideration for now:  malign: See http://lists.w3.org/Archives/Public/www-math/2011Sep/0001.html  malignscope "*Future* versions of MathML may provide an malignscope element that allows an alignment scope to be created around any MathML element [...]" (http://www.w3.org/TR/MathML3/chapter3.html#id.18.104.22.168) That is, malignscope isn't specified yet?  mfraction "[...] the non-MathML element mfraction (presumably in place of the MathML element mfrac) [...]" (http://www.w3.org/TR/MathML3/chapter3.html#id.22.214.171.124) So "mfraction" does not exist and is just a sample for wrong markup ?  monospaced The MathML3 spec index links to http://www.w3.org/TR/MathML3/chapter2.html#fund.attval but there is no "monospaced" element/attribute ?!?
It would be a good idea to report these errors or questions to the MathML WG.
http://lists.w3.org/Archives/Public/www-math/2011Dec/0003.html http://lists.w3.org/Archives/Public/www-math/2012Jan/0000.html I can prepare a patch for removing these bits.
Created attachment 586090 [details] [diff] [review] Patch
I tested this patch there: https://tbpl.mozilla.org/?tree=Try&rev=bf7895f8e2fb