Is there no other way that the issues you have could be addressed without introducing TeX-XeT?
The more we look at this the more it seems a very unfortunate step, introducing several incompatibilities with pdftex and luatex. Especially if there is a possibility of moving in the end to an Omega/luatex model for bidirectional support introducing a change at this point seems a strange choice. The extra nodes added here really are a backward step, my first suggestion of only conditionally adding them doesn't really work if boxes containing math are saved and used in different contexts. Especially now in the Texlive 2015 pretest period there is so little time to test any changes. Would it be possible to back it out this change at least until after TL2015 is released That would give time to investigate a more compatible way to address the issues? David -------------------------------------------------- Subscriptions, Archive, and List information, etc.: http://tug.org/mailman/listinfo/xetex