2.1.1759 Part 4 Section 14.4.2, left (Table Leading Edge Border)

a.   The standard specifies this additional element, semantically equivalent to the start element ("[ISO/IEC-29500-1] §17.4.36; start").

Word ignores this element if the start element ("[ISO/IEC-29500-1] §17.4.36; start") is present as a sibling.