The project management system is the set of tools, techniques, methodologies, resources, and procedures used to manage a project. It can be formal or informal and aids a project manager in effectively guiding a project to completion.
The system is a set of processes and the related control functions that are consolidated and combined into a functioning, unified whole.
The project management plan describes how the project management system will be used. The project management system content will vary depending on the application area, organizational influence, complexity of the project, and availability of existing systems.
The organizational influences shape the system for executing projects within that organization. The system will adjust or adapt to accommodate any influence imposed by the organization.
If a PMO exists in the performing organization, one of the functions of the PMO would typically be to manage the project management system, in order to ensure consistency in application and continuity on the various projects being performed.