Additional member system instance of mixed-member system
The additional member system (AMS) is a mixed electoral system under which most representatives are elected in single-member districts (SMDs), and the other "additional members" are elected to make the seat distribution in the chamber more proportional to the way votes are cast for party lists. It is distinct from parallel voting (also known as the supplementary member system) in that the "additional member" seats are awarded to parties taking into account seats won in SMDs (referred to as compensation or "top-up"), which is not done under parallel voting (a non-compensatory method).
AMS is categorised under semi-proportional electoral systems, differently from the mixed-member proportional representation (MMP). In practice, the way that proportional additional member systems work depends on the number of additional ("top-up") seats and the votes cast in a  specific election.the Bundestag, if there are more overhang seats than proportional seats, these have been added to the legal size of the parliamentIn 1976, the Hansard Society recommended that a mixed electoral system in a form different from the German be used for UK parliamentary elections, but instead of using closed party lists, it proposed that seats be filled by the "best runner-up" basis used by the German state of Baden-Württemberg, where the compensatory seats are filled by the party's defeated candidates who were the "best near-winner" in each of the state's four regions. It was the way that compensatory seats were allocated that made their report the origin of the additional member system, the term which the report also invented, which was then applied along with the much older "mixed system" by English-speaking writers on voting systems to West Germany's system and similar models until mixed member proportional (MMP) was invented for the adoption of the German system proposed for New Zealand in a royal commission report in 1986, which would explain why AMS and MMP have been used as synonyms. The system the Hansard Society proposed was eventually adopted but with closed lists instead of the "best runner-up" (popularly known in Britain as "best losers") provision for elections to the Scottish Parliament, Senedd and London Assembly, but not for that proposed for elections to the House of Commons.
This system was proposed by the Independent Commission in 1999, known as Alternative vote top-up (AV+). This would have involved the use of the Alternative Vote for electing members from single-member constituencies, and regional open party lists. However, contrary to the Labour Party's earlier manifesto promises, no referendum was held before the 2001 general election and the statement was not repeated.
The AMS system in use in the London Assembly would have been used for the other proposed regional assemblies of England, but after the overwhelming No vote in the 2004 North East England devolution referendum, the Government abolished all the regional assemblies in 2008-2010.
type of example of manifestation of representation of