2.1.50 Part 1 Section 17.3.1.19, numPr (Numbering Definition Instance Reference)

  • Article

a.   The standard states that when this element appears as part of the paragraph formatting for a paragraph style, then any numbering level defined using the ilvl element shall be ignored.

Word does not ignore this element within a paragraph style definition, and will exhibit unpredictable behavior when it is present.