The Master Production Schedule (MPS) is best defined by The Apics Dictionary, which is cited below.
A line on the master schedule grid that reflects the anticipated build schedule for those items assigned to the master scheduler. The master scheduler maintains this schedule and material requirements planning. It represents what the company plans to produce expressed in specific configurations, quantities and dates. It is not a sales item forecast that represents a statement of demand. It must take into account the forecast, the production plan and other important considerations such as backlog, availability of material, capacity and any other management policies and goals.