Embedded vs. Stand-alone Indexes
http://www.allegrotechindexing.com/news008.htm

Brown, Fred
Allegro Time!
2001

Abstract:

Selecting the right type of index can save you both time and money. You create an embedded index by entering index markers directly into your document. You then generate the index from the embedded markers. With a stand-alone index, you create the index as a separate text file using dedicated indexing software. Embedded indexes are used commonly for software documentation while stand-alone indexes are used extensively in book publishing.