2.1.1275 Part 1 Section 220.127.116.11, chExt (Child Extents)
For additional notes that apply to this portion of the standard, please see the notes for ext, §18.104.22.168(a).
a. The standard states that the child extents defined by the chExt element are used for calculations of grouping, scaling and rotating.
In Office, this element additionally defines the group scaling factor which is the ratio of the extents to child extents when the size of the child extents is nonzero. If the size of the child extents is zero or omitted, there is no group scaling.