The Clean Development Mechanism (CDM) under the UNFCCC sets a standard for generating credits (Certified Emission Reductions, CERs) from Kyoto-compliant projects. The projects must qualify through a rigorous registration and issuance process with the UN CDM Executive Board designed to ensure real, measurable and verifiable emission reductions. Backed by the UN, the CDM standard has a high quality standing; however the disadvantages are the bureaucratic procedures and high costs preventing many smaller projects from registering their activity and increasing prices for CERs.
So-called 'pre-CDM VERs' are generated from projects whose CDM registration is still pending. Until the registration is decided upon, no CERs are generated. However, emission reductions from these projects that were created before registration can be verified as voluntary credits.