MathML Document Repository

MathML Safe List

Short Version

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:

• any common attribute with HTML attributes for which need a sanitzation as done in HTML,
• the mphantom elements which should, ideally, be kept or replaced by an empty mspace element
• the maction elements which should, ideally, be replaced by an mrow element with the same children, and
• any annotation 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, then, be removed.

Detailed Version

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

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:

• the mphantom elements which should, ideally, be kept or replaced by an empty mspace element; if no other possibility exists, then remove it,
• the maction elements which should, ideally, be replaced by an mrow element with the same children; if no other possibility exists, then remove it, and
• any annotation 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, then, be removed.