This part sets forth general regulations governing the authority of Customs officers, and the location of Customs ports of entry, service ports and Customs stations. It further sets forth regulations concerning the entry and clearance of vessels at Customs stations and a listing of Customs preclearance offices in foreign countries. In addition, this part contains provisions concerning the hours of business of Customs offices, the Customs seal, and the identification cards issued to Customs officers and employees. [T.D. 77-241, 42 FR 54937, Oct. 12, 1977, as amended by T.D. 99-27, 64 FR 13675, Mar. 22, 1999]