English translation: margin voting system; margin election
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Explanation: Official US gov't translation. (Don't ask...)
Anyway, often there will be a number in front of it: for example, in an election for 100 seats with 110 candidates, it's a "10% margin voting system" because the ratio of losers to winners is 10 to 100.
The election itself (without the "yuan2ze2") is called a "margin election".