2.1.1684 Part 1 Section 22.214.171.124, sup (Superscript (Superscript object))
For additional notes that apply to this portion of the standard, please see the notes for oMath, §126.96.36.199(c) .
a. The standard says sup only specifies the superscript of sSup even though the schema also allows it as a child of sPre, sSubSup, and nary.
In Word, sup specifies the superscript of sSup, sPre, and sSubSup, and specifies the upper limit of nary.