Independent requirements and dependent requirements are the two main types of requirements you encounter when configuring SAP planning. This is what they are:
Planned Independent Requirements (PIR)
Planned Independent Requirements are planned production or sales quantities that are based on some sort of forecast procedure (e.g. Material Forecast or S&OP procedure). These numbers are used in MRP to calculate procurement and/or production quantities for a material.
(Planned) dependent requirements
Dependent requirements is demand that is dependent on another material. E.g. components of a bill of material are often planned on the basis of the demand for the material of which it is a part.
You plan to sell 200 bikes in the month of January 2009 based on sales in the same month of 2008. These 200 bikes is a Planned Independent Requirement for 01/2009.
Since every bike is produced using two pedals the 200 bikes you plan to sell in January 2009 results in 400 pedals you need to procure. These 400 pedals is a planned dependent requirement for 01/2009.
On the basis of these numbers MRP can calculate including current stock levels how much bikes and pedals you actually need to produce/procure.
Sometimes “old” planned independent requirements can negatively affect your MRP planning leading to an overstatement of procurement quantities. How you can get rid of these requirements is posted here.
Read about PIRs and Consumption-based Planning here.