(a) The certificate required for the interstate movement of a regulated article must, at all times during the interstate movement, be attached to the outside of the container containing the regulated article except as follows:

1. (1) The certificate may be attached to the regulated article itself if it is not in container; or
2. (2) The certificate may be attached to the accompanying waybill or other shipping document if the regulated article is identified and described on the certificate or waybill.