You can get an overview of the legal regulations delivered for both application areas of Customs Management in the general settings in Customizing for SAP GTS (menu path SAP Global Trade Services, edition for SAP HANA → General Settings → Legal Regulations → Define Legal Regulation).
Basically, due to technical reasons, Customs Management consists of two application areas: customs processing and transit/presentation. For the EU, Switzerland, and the United Kingdom customs processing includes all customs procedures except the transit procedure. If your company wants to use SAP GTS for both the transit procedure and other customs procedures, you have to implement both application areas.
For the United States, the transit/presentation application area supports the transfer of goods from the point of unloading in the territory of the port of entry, to a foreign-trade zone inside or outside this territory, as well as goods movements between two foreign-trade zones (transportation under permit to transfer and transportation in-bond).
For customs processing in Australia, China, some European countries, New Zealand, and the United States, delivery Customizing provides legal regulations that you should use. In SAP GTS, these legal regulations represent all customs-related legislation and provisions that apply in the respective country.
In the case of the EU Member States, for example, the individual legal regulations for customs processing cover both EU customs law, that is, the Union Customs Code (UCC) and its implementing provisions, as well as national law, administrative rules, and technical specifications for electronic communication with the customs authorities. The legal regulations delivered for opening and/or discharging a transit procedure in some of the Member States also include the Convention on a Common Transit Procedure with the EFTA States, Macedonia, Serbia, Turkey, and the United Kingdom.