MathML-core considers all elements and attributes of MathML-core (as listed in section 2.1 of MathML-core) as safe and not needing a sanitization except the following elements.
We recommend the Sanitzer API to sanitize MathML by keeping all elements and attributes except the follwing:
mphantom elements which should, ideally, be kept or replaced by an empty mspace element; if these replacements are not possible, the element should be removed.maction elements which should, ideally, be replaced by an mrow element with the same children or, if this replacement is not possible, should be replaced by its child nodes andannotation or annotation-xml element whose encoding attribute is of a media-type that is is either absent or is not among the trusted types or if it contains an href attribute: the element should be removed.MathML-core considers the following elements and attributes of MathML-core as safe and not needing sanitization:
Safe “as-is” Elements of MathML-core:
math, merror, mfrac, mi, mmultiscripts, mn, mo, mover, mpadded, mprescripts, mroot, mrow, ms, mspace, msqrt, mstyle, msub, msubsup, msup, mtable, mtd, mtext, mtr, munder, munderover, semantics
Safe “as-is” attributes of MathML-core:
dir, displaystyle, mathbackground, mathcolor, mathsize, scriptlevel, encoding, display, linethickness, intent and arg; on mo elements: form, fence, separator, lspace, rspace, stretchy, symmetric, maxsize, minsize, largeop, movablelimits; on mpadded elements: width, height, depth, lspace, voffset, on mspace elements: width, height, depth, on munderover elements accent and accentunder; on mtd elements columnspan and rowspan.
Moreover, the following attributes have their syntax and semantics specified in the HTML specification. The sanitizer behaviour on these attributes should be as is done on HTML elements: on*, id, class, style, data-*, autofocus, nonce,tabindex (for example any javascript should be removed).
The elements of MathML-core which need treatment by the sanitizers are the following. The proposed replacements are expressed in order of preference:
mphantom elements which should, ideally, be kept or replaced by an empty mspace element; if this replacement is not possible, the element should be removed it,maction elements which should, ideally, be replaced by an mrow element with the same children; if this replacement does not exist, then replace by its child nodes, andannotation or annotation-xml element whose encoding attribute is of a media-type that is is either absent or is not among the trusted types or if it contains an href attribute: the element should be removed.