5. A work or other subject matter shall be deemed to be out of commerce when it can be presumed in good faith that the whole work or other subject matter is not available to the public through customary channels of commerce, after a reasonable effort has been made to determine whether it is available to the public.
Member States may provide for specific requirements, such as a cut-off date, to determine whether works and other subject matter can be licensed in accordance with paragraph 1 or used under the exception or limitation provided for in paragraph 2. Such requirements shall not extend beyond what is necessary and reasonable, and shall not preclude being able to determine that a set of works or other subject matter as a whole is out of commerce, when it is reasonable to presume that all works or other subject matter are out of commerce.