2.1.1626 Part 1 Section 21.4.3.7, spPr (Shape Properties)

For additional notes that apply to this portion of the standard, please see the notes for spPr, §20.5.2.30(a-c).

a.   The standard states that the grpFill element is a valid child of the spPr element.

Office will display an empty (invisible) shape fill for any diagram shape with a group fill, regardless of the fill of the parent group.