•PDD
Project Design Document. The official application drawn up by an entity applying for project approval under the Clean Development Mechanism (CDM). PDDs must be validated by an independent third party, then approved and registered by the CDM Executive Board before a project qualifies as a CER carbon credit earner.
•tCO2e, MtCO2e 
Tons of carbon dioxide equivalent, and millions of tons of carbon dioxide equivalent. This is the metric measurement unit for greenhouse emissions. The global warming impact of all greenhouse gases is measured in terms of equivalency to the impact of carbon dioxide (CO2). For example, one million tons of emitted methane, a far more potent greenhouse gas than carbon dioxide, is measured as 23 million tons of CO2 equivalent, or 23 MtCO2e.

•VERs
Verified Emission Reductions. Tradable credits for greenhouse emission reduction activities generated to meet voluntary demand for carbon credits by organizations and individuals wanting to offset their own emissions.