Article 51 establishes the principle of tax-free movement of goods between Designated Zones. It explicitly states that goods may be transferred from one Designated Zone to another without any tax becoming due. The article further delegates procedural implementation to the Executive Regulation of the associated Decree-Law. This regulation is tasked with specifying the precise procedures and conditions governing the transfer of goods both to and from a Designated Zone. Additionally, the regulation will outline the approved mechanisms for the keeping, storing, and processing of such goods within these designated areas, ensuring full regulatory compliance.