2.1.1503 Part 4 Section 188.8.131.52, invertIfNegative (Invert if Negative)
a. The standard states that the default value of the val attribute is true.
Office uses a default value of false for this attribute.
This note applies to the following products: 2007, 2007 SP1, 2007 SP2.
b. The standard does not state any exceptions that cause this element to be ignored.
Office ignores this element and always inverts the negative values if the ancestors include bubbleChart.