2.1.189 Part 1 Section, customXml (Row-Level Custom XML Element)

For additional notes that apply to this portion of the standard, please see the notes for oMath, §; oMathPara, §

a.   The standard states that the element attribute can contain any string value.

Word only allows values conforming to the XML specification; a string conforming to the definition of xsd:NCName with a length of at most 255 characters.