D.C. Mun. Regs. tit. 18, r. 18-407
When the Director is satisfied that an applicant for a certificate is entitled to registration as a prorated interstate bus, and the applicant either does not designate the District as a base state for purposes of registration, or designates the District as a base state for purposes of registration but requests no identification tags, a certificate shall be prepared in the form prescribed by the Director.
The certificate may incorporate by reference a list of vehicles to be covered by that certificate. The list shall contain a description of each vehicle.
The certificate shall be retained by the Director for record purposes and shall not be issued to any person.
If an applicant designates the District as the base state and requests identification tags for the vehicle, the application shall be processed pursuant to the provisions of §§ 400 and 403.
D.C. Mun. Regs. tit. 18, r. 18-407