When reporting percentile ranks, we typically read them as ordinal numbers (e.g. 2nd percentile) rather than real numbers (e.g. 2 percentile). A switch can be used to make that change automatically when the REF field displays the data (see pg 10 of the Tutorial PDF).
To switch a number (5) to an ordinal (5th), the switch \*ordinal is added to the end of the REF field.
The syntax is this:
{ REF Bookmark \*ordinal }
Notice that this does not work with percentile ranks less than 1 (e.g. 0.1 percentile). In fact, Word will display this as "0th percentile." IF fields can rectify that issue (see pg 11 of the Tutorial PDF).