2.1.125 Part 4 Section 2.4.13, gridSpan (Grid Columns Spanned by Current Table Cell)
For additional notes that apply to this portion
of the standard, please see the notes for tcPr, §18.104.22.168(a); tcPr, §22.214.171.124(b).
a. The standard allows a gridSpan to have a
value of 0.
Word treats a gridSpan of 0 the same as a grid span