A uniform price auction may be utilised to aggregate a number of units offered by more than one seller to multiple buyers. This style of auction, sometimes referred to as a "call market" or double auction, shares the characteristics of an open market mechanism in which all buyers and all sellers interested in trading a homogenous commodity may participate simultaneously. The clearing price mechanism is often utilised in a market context in order to establish a benchmark price index for that market in question. Examples include government bond auctions, energy market auctions and compliance certificate markets.