2.1.330 Part 1 Section 184.108.40.206, ins (Inserted Math Control Character)
a. The standard does not state that the del element is a valid child.
Word allows the del element to be a child when a math control character is part of both a tracked insertion and tracked deletion.
b. The standard states that the rPr (Previous Run Properties) element is a valid child.
Word allows the rPr (Run Properties) element, not the rPr (Previous Run Properties) element, to be a child.
c. The standard states that the minOccurs value for the rPr child element is 1.
Word does not require an occurrence of this element.