The names and codes of districts and ports are listed in Schedule D, Classification of U.S. Customs Districts and Ports for Foreign Trade Statistics. The geographical limits of each district are published in the U.S. Customs Regulations. Schedule D is published as a statistical annex in HTSA and as a part of Schedule B. Statistics for two or more Customs Districts may be combined and published under an arbitrary designation or shipping weight may be excluded from an individual Customs District as a solution to disclosure situations. Consequently, statistics for individual ports may be understated due to the suppression of the weight of the affected commodities.