aircraft. The new register came into force on 22 July 1919; aircraft flying on temporary former military serials and those allotted in the K-100 sequence were all re-registered sequentially from G-EAAA. G-EAAA to G-EZZZ Heavier-than-air aircraft. G-EAAA to G-EBZZ and G-EDCA were allocated. G-FAAA to G-FZZZ Lighter-than-air aircraft. G-FAAA to G-FAAX were allocated. G-AUAA to G-AUZZ was allocated to Australia (1921–1929) replaced by VH-xxx. G-CAAA to G-CAZZ was allocated to Canada (1920–1929) replaced by CF-xxx. G-CYAA to G-CYZZ was allocated to Canada for government and military aircraft (1920–1929). G-IAAA to G-IAZZ was allocated to India (1920–1928) replaced by VT-xxx. G-NZAA to G-NZZZ was allocated to New Zealand (1921–1929) replaced by ZK-xxx. G-UAAA to G-UAZZ was allocated to the Union of South Africa (1927–1929) replaced by ZS-xxx. Second permanent register 1928- At the 1927 International Radio-Telegraph Conference the United Kingdom was allocated radio callsign prefixes B, G, M, VP, VQ and VR. Within this new allocation the United Kingdom continued to use the prefix G- for all aircraft but the sequence was restarted at G-AAAA, which continued into the 21st century. The first registration in the sequence, G-AAAA, was allocated to a de Havilland Gipsy Moth, registered on 30 July 1928 to Geoffrey de Havilland. At first nearly all registrations were issued in sequential alphabetical order but since the 1970s personalised ("out of sequence") registrations are available using any four-letter combination. Except in very rare circumstances, no registration is ever re-issued to a different aircraft. Countries in the British Empire that had used the G- prefix were allocated new two-letter allocations. The oldest flyable aircraft in the world as of 2011, a Humber-built Bleriot XI from 1909 owned by the Shuttleworth Collection in the UK, still uses the very early form registration G-AANG. Microlights From 1981 until 1998 most microlights were registered in the G-MBAA/MZZZ sequence but that system was officially discontinued and microlights have since been registered with any unused suffix. Gliders In 1937 the sequence G-GAAA to G-GAAE was used for five gliders to operate in an international competition in Germany. To comply with the regulations of the European Aviation Safety Agency, all gliders have had to be registered and marked externally in the G-xxxx sequence since 2008, except for a small group of specified vintage types known by the name of the EASA document, Annex 2. From 1930 to 2008, existing gliders did not need to be registered