.dd part of the Federal Republic of Germany, which had already been assigned the ccTLD .de. The ISO 3166-1 code "DD" was withdrawn in 1990. .dd .dd was the assigned country code top-level domain (ccTLD) for the German Democratic Republic (East Germany). It was chosen based on the ISO 3166-1 alpha-2 code for the German Democratic Republic, the letters coming from the German name of the country: '. In accordance with IANA policy, .dd was therefore available to be assigned as the country code top-level domain (ccTLD) for East Germany. However, this was never done, and so .dd was never added
Generic top-level domain that was explicitly chartered as unrestricted. The others initially had a specific target audience. However, due to lack of enforcement, they acquired an unrestricted character, which was later grandfathered. The term sponsored top-level domain is derived from the fact that these domains are based on theme concepts proposed by private agencies or organizations that establish and enforce rules restricting the eligibility of registrants to use the TLD. For example, the aero TLD is sponsored by the Société Internationale de Télécommunications Aéronautiques, which limits registrations to members of the air-transport industry. The new gTLD programme saw the arrival of many such