>How it's possible for a form to decide is somethiong changed or not? Maybe record or data pointer was changed by some other form?

Well, that's exactally the point. With private data session you treat each form as if it is it's own user... so, multi-form and multi-user conflicts are the same... the Private DataSession eliminates the conflicts WITHIN the same set of work areas so you don't have to have all the code that manages the same file opened multiple times by many forms with aliases.

BOb