Explanation:

The Kyoto Protocol sets emissions targets for developed countries which are binding under international law. Annex-I countries are related to Kyoto Protocol. Annex I Parties include the industrialized countries that were members of the OECD (Organisation for Economic Co-operation and Development) in 1992, plus countries with economies in transition (the EIT Parties), including the Russian Federation, the Baltic States, and several Central and Eastern European States.

The Clean Development Mechanism is one of the Flexible Mechanisms defined in the Kyoto Protocol that provides for emissions reduction projects which generate Certified Emission Reduction units which may be traded in emissions trading schemes.  It allows countries that have emission units to spare - emissions permitted them but not "used" - to sell this excess capacity to countries that are over their targets.