(1) Where the owner permits another person to appropriate products or other components of the thing, the other person acquires the ownership of them, if possession of the thing has been made available to that other person, on separation, or otherwise on taking possession. If the owner is obliged to permit this, then the owner may not revoke permission as long as the other person is still in the possession of the thing that was made available to them.
(2) The same applies if the permission comes not from the owner but from another person to whom products or other components of a thing belong after separation.