>Can I set the SET DELETED ON during the starting of my progrma in main.prg? Then I do not want to bother it anymore, will it have any effect when i am in the private data session?

If you set DELETED ON in your main program, it will only affect tables opened in the default datasession. Each datasession respects it's own TALK, ECHO, DELETED et al. This is why it is important for you to place these SETS in one of the starting events in a form with private datasession, preferably in the DataEnvironment. As I stated before, my personal preference is to put all my SETs in the BeforeOpenTables event of the form's DataEnvironment.