To create an index in Word, you need two components, the INDEX field (which
displays the result of the index) and XE fields (which represent individual
index entries in the document). On the References tab, you can click the
Mark Entry button to mark text for inclusion in the TOC, and you can use the
Insert Index button to add indexes to your document; the procedure creates
the required XE and INDEX fields.
If you want several different indexes, you must edit the appropriate XE
fields to include the \f switch. Display hidden text in order to see the XE
fields. Specify, say, \f "t" for one set of fields, and \f "g" for another
set of fields. Then create one INDEX field with the \f "t" switch and
another with the \f "g" switch.
In order to show/hide the INDEX field code (as well as the codes for any
field that is not formatted as hidden text), you can use Alt+F9.