ECEP01150 - Introduction: The law
The current legal basis for each trading Agreement between the UK and those countries that grant preferential treatment to goods that originate in the UK is contained in various origin reference documents. They only relate to trade between the UK and the partner countries concerned. Most trade agreements are bilateral (2-way), meaning the UK exports to and imports from the country. More information on the UK's trade agreements can be found here: UK trade agreements in effect - GOV.UK (www.gov.uk)
The UK's Developing Countries Trading Scheme (DCTS) is a unilateral scheme, where only imports are made into the UK from a range of developing countries.
The origin reference documents are a means from which the international law is implemented into UK domestic law, and provide for the administration of the agreements and lay down the rules of origin.
An up-to-date list can be found on Gov.UK at: https://www.gov.uk/government/publications/reference-documents-for-the-customs-tariff-preferential-trade-arrangements-eu-exit-regulations-2020