ViewModels has a rooted AccessExpression that should return true or false (empty defaults to true). This expression controls if the ViewModel is shown or not - the evaluation is done after any accessgroup evaluation. This expression complements the accessgroups as this has the ability to check the root objects values and not only global values as accessGroups.

The AccessExpression can be checked prior to ViewModel creation with the ocl CanAccess operator.

Prior to 2021-02-01 the AccessExpression and AccessGroup.ViewEnableExpression had issues in both WPF and Turnkey - but is now fixed.