There is something in the processing of mathml I do not understand. I keep the xml-node in a \startxmlsetups my:setup \def\mynode{#1} \stopxmlsetups Doing \xmlflush{\mynode} does typeset the contents of mynode, but not when mynode contains a mathml tree! Then the error is: Undefined control sequence ... \MMLhack ->\let \MMLpar \par \let \par \relax \everyvbox {\let \par \MMLpar } \12>:mml:math ...}} {\automathematics }}{\MMLhack \xmlflush {#1}}\endgroup Tested it with a simple: <math xmlns='http://www.w3c.org/mathml' version='2.0'> <apply><root/> <ci> x </ci> </apply> </math> The strange thing is, when putting the mathlml tree insize <text> mathml-content </text> where: \startxmlsetups xam:text \xmltrim{#1}\par \stopxmlsetups then typesetting goes without an error! Can someone explain this behaviour? Hans van der Meer