Well,
having said that this is related to an ERP system earlier: Large companies (where this may cause a problem in the first place) typically apply naming policies for their accounts. So users do not have free choice of their account names. If you need your customers to auto-create their accounts (a very typical e-commerce-shop scenarios) their unique account is sufficiently specified by their mail address as was said earlier on this thread. Alternatively, alike many free mail-providers, you could have your users specify their wish and come up with alternative solutions if that userid is not free any more. I personally think that for an ERP system, any critical fundamental ResourceId should NOT be re-usable. Think of others like e.g. a WarehouseId, a CompanyId ... even down to more "volatile" entity-ids like , a ProductId, a ContentId, a DataResourceId etc. That's why an Id is a unique Id anyways, i.e. if it is not unique within the scope of the running environment (at least, if not Global), why is it considered an Id? Kind regards Carsten
