Adjective or locution showing that the absence of something is required?

Is there any short way to say that something must be absent? If something must be present, I’d use "is required", but what can replace "must be absent", and only that? Words like "unexpected" don’t fully fit the meaning I’m looking for.

This request relates to programming and I’m not sure if there is such a way to convey in a short manner, and that could be written in way to oppose "required".

The full concept is that I setup group requirements. An object may have any number of components, but to be part of a group, they must obey the group’s requirements. The group says that it accepts all objects that have some components, but rejects those that have some other components.

I’d use it in a sentence similar to:

From the point of view of the group, some specific components are required and some other specific components are __________.

And it could be also written as:

From the point of view of the group, some specific components are required and some other specific components must be absent.