2.1.151 Part 1 Section 17.4.39, tblBorders (Table Borders Exceptions)

a.   The standard specifies a method for resolving border conflicts.

In Word, when cell spacing is nonzero, insideH and insideV table-level exception borders may still conflict with cell borders.  If there is a border conflict, it shall be resolved using the method describe in tcBorders ("[ISO/IEC-29500-1] §17.4.66; tcBorders (Table Cell Borders)").

b.   The standard says that if cell spacing is nonzero, then there is no border conflict even though insideH and insideV table exception borders may conflict with cell borders.

In Word, when cell spacing is nonzero, insideH and insideV table exception borders may still conflict with cell borders.