Frédéric Wang (:fredw) 2012-05-06 07:39:10 PDT "An mpadded element renders the same as its child content, but with the size of the child's bounding box and the relative positioning point of its content modified according to mpadded's attributes." MathJax uses mpadded to implement many LaTeX commands. Some reftests: http://devel.mathjax.org/testing/testsuite/MathMLToDisplay/Presentation/GeneralLayout/mpadded/