CHIEF: document types, codes and associated classes for box 40
Document types along with the code to be declared and the associated class(es) for box 40.
Documents
Details
If you are making a declaration using the Customs Declaration Service (CDS) follow the guidance in the UK Trade Tariff: volume 3 for CDS.
Usage table for box 40 which lists the document types along with the code to be declared and the associated class or classes to use.