The project design document (PDD) is the main document required to develop and register a CDM project. It describes the project, establishes the baseline methodology and monitoring plan, and calculates emission reductions. The PDD is reviewed during validation by a designated operational entity and submitted to the Executive Board for registration. It forms the basis for stakeholder consultation on the proposed project. Specific PDD templates exist for different project types like large-scale, small-scale, afforestation/reforestation, and programmatic projects.