Hi: These are files created by the Transfer program. The IX file has to do with navigation and the AA file has to do with holding your place in a file. In the case of Book Share books, if it's a Daisy file, you would send the OPF file. Daisy files are made up of multiple files. Even though you're only sending one file, it gets the information from the other files that make up the book. Pamela Rader, TECHNICAL SUPPORT American Printing House For The Blind 1839 Frankfort Ave. Louisville, KY 40206 PHONE: 1-800-223-1839, Ext. 307 >>> girlyscream@xxxxxxxxxxx 08/23/07 05:59AM >>> What is the purpose of the ix and aa file types on the hidden files? Also, when transferring the .bp file from vookshare to the book port, how can such a small file contain the entire book? Thanks, Nancy