2.1.589 Part 4 Section 2.18.100, ST_TextDirection (Text Flow Direction)
a. The standard states that tbLrV orients lines from top to bottom, left to right and tbRlV orients lines from top to bottom, right to left.
Word uses the text direction specified by tbLrV for both tbLrV and tbRlV.
b. The standard states that btLr orients the text from bottom to top, then left to right.
Word does not respect this value when used at the section level.