2.1.1473 Part 1 Section 21.2.2.73, forward (Forward)

a.   The standard states that the value of the val attribute on non-scatter charts must be a multiple of 0.5.

Office allows the data range to include any non-negative number.

b.   The standard states that attribute val is of type xsd:double.

Office does not allow INF, -INF, and NaN as supported values.  For scatterChart and bubbleChart, the value is in units, otherwise the value is in number of categories. The value of this attribute has a minimum value greater than 0.