ERP/MRP is one of the resources of the organization to run the business. As such, it has to be considered as an integral part of QMS and not as an "external body".
As a simple example to make it real, it could be that inside ERP/MRP there are lots of data pertaining to the business, whose retention is requirement.
As a simple example to make it real, it could be that inside ERP/MRP there are lots of data pertaining to the business, whose retention is requirement.