You can safely add your index to the table, it should not affect other programs if they are not aware of this new index. The new index will be stored permanently in the CDX file.

It could slow down updates in the table because the new index will need to be updated, but it's pretty much negligible.

In VFP, the index and the table are 2 different entities. You need to apply an index to the table to affect the order of the record. So you don't have to worries about affecting the table structure.

HTH

>Beginner programmer question:
>
>I'm reworking a VFP6 database written by another programmer using tables from an FPW26 app (which is still being processed in part by FPW26). The main table has a field named 'LNAME' which has a regular ascending index.
>
>However, for this routine, I really need an index tag for UPPER(LNAME).
>
>If I create this index within the routine using INDEX ON UPPER(LNAME) TAG LAST ASCENDING, will the new index be added to the .CDX file, or will it exist only for the current session? Will it cause 'index bloat'? Will it alter the index structure of the table? Are there any other considerations I should be aware of?