2.1.1084 Part 1 Section 18.18.47, ST_NumFmtId (Number Format Id)

a.   The standard states that the values of the ST_NumFmtId simple type are defined by the XML Schema unsignedInt datatype.

Office restricts the values of this attribute to be at most 65535.

b.   The standard does not restrict the values of instances of the ST_NumFmtId simple type.

Office requires the first instance of this type in any sequence to be equal to zero. This instance specifies the default style.