(1) The headend, in the case of a cable system with a single headend or,
(2) In the case of a cable system with more than one headend, the principal headend designated by the cable operator, except that such designation shall not undermine or evade the requirements of subpart D of this part. Each cable system must provide information regarding the designation and location of the principal headend to the Commission promptly upon request. Except for good cause, an operator may not change its choice of principal headend. Cable systems may elect voluntarily to provide the location of the principal headend in the Commission's online public inspection file database and may choose whether to make this information accessible only by the Commission or to also make it publicly available. Systems that elect not to provide this information in the online file, or to protect this information in the online file from public view, must make it available to broadcast television stations and local franchisors upon request. If a request is submitted by a television station or franchisor in writing by certified mail, cable systems must respond in writing by certified mail within 15 calendar days. Cable systems may in addition elect to respond to requests from these entities submitted by telephone or email, but must respond in writing by certified mail if requested to do so by the station or franchisor.