jlockley,
Maintained indexes are rebuilt whenever any field value in the index's fields is updated or modified. Practically speaking, if you have a maintained index and add ten records, the index is rebuilt ten times.
As you might expect, this slows the update process (e.g. posting of a record), but ensures that index-based locates, ranges, and other activities are as quick as possible. Maintained indexes are best used in applications that involve more searching than editing.
Non-maintained indexes aren't updated when the table is. Instead, they're flagged as being out of date. When you perform an index-based operation on an out-of-date index, Paradox rebuilds the index before performing the operation. Thus, certain ranges, locates, etc may be slow the first time you perform them, but then they're as fast as usual--until the index is out of date again.
Non-maintained indexes can improve data entry, but slow research operations.
Both types are very useful for specific operations and most well-design Paradox applications mix the two, depending on the needs of the programmer and the users.
The type of index is controlled by clicking the Maintained checkbox when creating the index using the Restructure dialog.
Hope this helps...
-- Lance