Only on the related into expression and the table's current order must be that tag. If no index is set and expression is integer then it is assumed to be related on RECNO().

However, as stated and sampled in your related < g > question you don't have a need for set relation.

>Hi,
>
>When you SET RELATION TO, in order to update one cursor from another, do both cursors have to have the index build (and set) on the field used for the relation?
>
>The reason I am asking is when I was doing a small test of two cursors I only created an index on the Target cursor (the one which has the SET RELATION TO set). And it worked in my test case. But when I do it in the program code, it does not work. But once I build an index on the cursor TO which the relation is set, it works.
>What am I missing?
>
>TIA