2.1.728 Part 1 Section 188.8.131.52, cacheFields (PivotCache Fields)
a. The standard states that the maxOccurs value for the cacheField child element is unbounded.
Excel limits the occurrences of this element to 1024 when the value of the createdVersion attribute on the pivotCacheDefinition element is less than 3 and 16384 otherwise.
b. The standard states that the minOccurs value for the cacheField child element is 0.
Excel requires an occurrence of this element for non-OLAP PivotCaches.