It is important to understand that the input to a phase process group is the output from the previous phase group process. That is, the inputs that are going into the execution process group requires the use of the the documentation from the planning process group. Without a Project Management Plan, Quality Management Plan, Work Breakdown Structure, Risk Management Plan, etc. the start of executing the project does not follow through as effectively. Also, many of these plans are living documents that are updated through the execution of the project, because the planning and execution process groups are cyclical. The outputs of the execution process group will go as inputs to the planning process group to update the planning documentation. The outputs of the execution is therefore logged in the changes made to the planning phase documents as more details are sorted out.