>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!

HackFox3 says "In fact, the only reason to use stand-alone indexes at all is to maintain compatibility with other products or older versions that can't read compound index files."

Maybe the app was developed when either of the above were true.

An interesting Google find: https://books.google.ca/books?id=wKNfTHRNkLAC&pg=PA219&lpg=PA219&dq=vfp+standalone+index+file&source=bl&ots=_-bUpZTkWG&sig=w7tIYUSJv1ZNjKCdxlwqhkm6AIU&hl=en&sa=X&ved=0ahUKEwjZrqr_0djOAhUBymMKHchgBAcQ6AEIRjAI#v=onepage&q=vfp%20standalone%20index%20file&f=false

A discussion of the various index types: https://msdn.microsoft.com/en-us/library/xb5dh76z(v=vs.80).aspx