2.1.1608 Part 1 Section 21.3.2.21, relSizeAnchor (Relative Anchor Shape Size)

a.   The standard allows shapes to be defined where the right edge is to the left of the left edge or where the bottom edge is above the top edge.

Office places additional restrictions on the relative size of 'from x' and 'from y’ as follows:

The left side (from x) should be less than or equal to the right side (to x).

The top side (from y) should be less than or equal to the bottom side (to y).

If these restrictions are not met, Office uses the values described in the 2D transform (xfrm), if they are valid. If these values are not valid, Office does not render the shape.

b.   The standard states that the from element specifies the top left corner of the shape bounding box in a RTL (right to left) implementation and the to element specifies the bottom right corner of the shape bounding box in a RTL implementation.

In Office, the from element specifies the top left corner of the shape bounding box relative to the chart and the to element specifies the bottom right corner of the shape bounding box relative to the chart.