True, I agree with the `Is` thing. That was a bad idea.

I still think that something like `Sharing` is not correct here: The intended audience for this library should not have to know anything about eR/backend. So they don't know that this activity is shared between eR & CompanyPortal (and they don't care about that). I agree that `Visibility` is not very good, but I still think `Sharing` is not right in regard to the intended library consumer. How about a compromise like `ApplicationActivityAvailability` and `AvailableToContact` (very long, I know, but I'm running out of ideas).

In addition, I just realized that the enum-values are not entirely correct. It's not just `Visible` and `Executable`, because the activities of both kinds can be executed. The difference is that "small" activities just trigger a workflow-jump and a simple message to the eR user, while the other, "big" activities trigger a workflow-jump and the entire communication thing with the applicant or contact. How about `None`, `Simple`, `Full` or something like that (this would work nicely with `Availability`)?