2.1.509 Part 1 Section 17.16.11, default (Default Drop-Down List Item Index)
a. The standard says that if the value exceeds the number of items in the drop-down list, then drop-down list defaults to its first entry.
In Word, if the value exceeds the number of items, then the drop-down list defaults to an empty entry.
b. The standard states that the values of the val attribute are defined by the XML Schema integer datatype.
Word restricts the value of this attribute to be at least 0 and at most 24.