2.1.1419 Part 1 Section 18.104.22.168, backward (Backward)
a. The standard states that the value of the val attribute on non-scatter charts must be 0 or 0.5.
Office allows the data range to include any non-negative number.
b. The standard states that the values of the val attribute are defined by the XML Schema double datatype.
Office restricts the values of this attribute to be greater than 0 and not equal to INF, -INF, or Nan.