Maintenance
Service Part Requirements  [1]
Preventive Maintenance Schedule Integrated with Production schedule . Preventive maintenance needs to be planned into the production schedule[2]
MRO                                                        MRO is the abbriviation for "Maintenance, repair,and operating suppliers.[3]
[1]
When service part requirements are for major assemblies they are often master scheduled.  The dependent demand for the sub-assembly, I.e., the requirement created by a higher level product, is combined with the service part requirement and controlled in the MPS, even if the dependent demand is actually higher than that for the service part.
 
[2]
Enas refaat:
Unplanned downtime of equipment is likely to cause planned work to become overdue.  If it is not possible for the manufacturing orders to "catch up" the original schedule, they could affect the validity of the MPS unless they are rescheduled, and cause delay in  the shipments to customers.
In an effort to prevent or reduce this problem the concept of preventive maintenance is introduced. 
[3]
We normally have to hold stocks of spare parts for the machinery in our factories to enable the maintenance engineers to keep the equipment running, and to repair it if it breaks down.  This inventory  is ususally kept in a separate store known as the engineering stores. The inventory and the  replenishement of it is under the controlof the maintenance engineering departement.