An assigned amount unit was a tradable "Kyoto unit" or "carbon credit" representing an allowance to emit greenhouse gases comprising "one metric tonne of carbon dioxide equivalent, calculated using global warming potentials".[1][2] Assigned amount units were issued up to the level of initial "assigned amount" of an Annex 1 Party to the Kyoto Protocol.[3][4]
The "assigned amounts" were the Kyoto Protocol Annex B emission targets (or "quantified emission limitation and reduction objectives") expressed as levels of allowed emissions over the 2008–2012 commitment period.[5]