>I have a multi-detail band report. The target alias for band 2 (child band) is using an index tag on, say ORDER_NO. This is necessary for the SET RELATION statement of the parent alias (band 1) to work. But I want the report to show the items in the band 2 in a certain order (not just random order). For example, say I want the order to be by the PK value (ORDER_PK). I thought that I could create index tag on expression STR(ORDER_NO,6) + STR(ORDER_PK,6). I am not sure this will work and if it does, will it slow down the execution?

It will work as long as you have SET EXACT OFF. I'm not sure why it should slow down execution besides the time for creating an index, if it'd done dynamically.