2.1.1506 Part 1 Section 188.8.131.52, pivotSource (Pivot Source)
a. The standard states that the maxOccurs value for the extLst child element is unbounded.
Office limits the occurrences of this element to 1.
b. The standard states that possible values for child element fmtId are defined by type xsd:unsignedInt.
In Office, child element fmtId has a maximum value of 2147483647.