>I'm working with an application where they author of the app is using only free tables, and idx vs cdx indexes. I understand all the issues with the free tables and not having them in a DBC -- but I've never even used IDX indexes. I'm wondering if there are any advantages or disadvantages to using IDX indexes. Thanks!

A couple of people have hinted at this, but I want to say it explicitly. If you add or change records in a table and a particular IDX is not open, that IDX is not updated. There is NO reason to maintain IDXs in 2016. There might occasionally be a reason to create one temporarily.

Tamar