Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Precedence Diagram Method is a tool for scheduling activities in a project plan. It is a method of constructing a project schedule network diagram that uses boxes, referred to as nodes, to represent activities and connects them with arrows that show the dependencies. A project plan, according to the Project Management Body of Knowledge, is "...a formal, approved document used to guide both project execution and project control. The primary uses of the project plan are to document planning assumptions and decisions, facilitate communication among stakeholders, and document approved scope, cost, and schedule baselines. A project plan may be summarized or detailed." In some industries, particularly information technology, the term "project plan" can refer to a Gantt chart or other document that shows project activities along a timeline. While common, this use is inaccurate. These types of documents are more accurately described as "project schedules" and are only one component of a true project plan.