2.1.1376 Part 4 Section 184.108.40.206, fillToRect (Fill To Rectangle)
a. The standard states that the center shade fills the entire tile except the margins specified by each attribute.
In Office the center shade fills the entire gradient path inscribed in this rectangle.
b. The standard states that the Rectangle is defined relative to the tile rect.
In Office the rectangle is defined relative to shape bounding box.