2.1.509 Part 4 Section 184.108.40.206, INDEX
a. The standard does not list \o as a switch for the INDEX field.
Word adds a \o switch that is used with the INDEX field to specify sort order. The text in this switch's field-argument specifies the sort order for Chinese, S for sorting by strokes within radicals and P for sorting by pronunciation. By default, sorting is by strokes.
b. The standard says that if the \f switch is omitted, the index will include all entries.
In Word, if the \f switch is omitted, the index will contain only those entries also lacking \f switches.
c. The standard does not limit the length of the field arguments for switches \d, \e, \g, \k, and \l.
In Word, the \d, \e, \g, \k, and \l switches are all limited to 15 characters.