2.1.754 Part 1 Section 18.10.1.26, discretePr (Discrete Grouping Properties)

a.   The standard says discretePr represents the collection of discrete grouping properties for a field group.

In Office, each child element specifies a mapping from an element in the sharedItems collection ("[ISO/IEC-29500-1] §18.10.1.90; sharedItems (Shared Items)") of the base field of this field group to an element in the groupItems collection ("[ISO/IEC-29500-1] §18.10.1.38; groupItems") of the field group, using a zero-based index into the groupItems collection. The number of child elements shall match the number of elements in the sharedItems collection ("[ISO/IEC-29500-1] §18.10.1.90; sharedItems (Shared Items)") of the base field of this field group.