MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 11: Integrated Indexes
The current index range is unaffected by updates, deletes, and inserts.
Whether and where changed rows are visible within the current range depends on the rules governing visibility of changes in the index. For example, suppose the range on an index column is "A" to "L" and the last row fetched had a value in this column of "H". If the value of that column in a currently held row is changed from "B" to "K", if the change is transmitted to the data store, and if transmitted updates are visible in the index, the row will be fetched if the consumer completes the scan to the end of the range. If the value of the column is changed instead to "M" and transmitted, the row will not be fetched.