The first widely used production planning software had the same acronym but with a different meaning. The original MRP meant material requirements planning. This takes target dates for finished products, and works backwards to determine a production plan and raw material purchasing plan.
MRP II (spoken as “MRP-two”) extended MRP by handling at least financial and forecast data, and sometimes engineering and human resources. MRP II translates forecasts into master production schedules; maintains bills of material (lists of product components); creates work orders for each step in the production routing; tracks inventory levels; coordinates materials purchases with production requirements; and generates reports.
The progression from MRP to MRP II continued, and the next generation gained the name ERP (Enterprise Resource Planning).