The link or interface between each process must be clearly defined and well managed. A process is documented by writing procedures. Your quality system should be documented by writing procedures. If you document your current quality system procedures, changes in quality are easier to detect and to measure because they can be compared with the way things were done in the past. Procedures have been approved.
Procedural changes are under control.
That's what the following material will now do. Use ISO 9000-2 if you need some help implementing ISO 9001, ISO 9002, or ISO 9003. Use ISO 9000-3 if you are in the software business and you want to use ISO 9001 to set up a quality system. Use ISO 9000-4 if product dependability is important. Dependability means reliability, maintainability, and availability.