Sorry @apmShould have explained ECN, it stands for Engineering Change notice, which is a request coming in to the Engineering department requesting a change to an Engineering document be it a drawing, procedure or specification. This system works well to prioritise problems and works particularly well when it’s all laid out in front of people and they can see the logic, ie if the boss asks for something to be done then you see where it fits in the matrix and often he's request comes out fairly low, if presented well and you have a reasonable boss they can see the logic and leave you to get on with your job. Of cause if you have an unreasonable boss then maybe it’s time to look for other opportunities. This also is useful when you have several problems as you give each a score and then the one with the highest score gets worked on first. With Maximum score of 30. A few years back I worked in a Multinational company with facility around the world and this is the system they implemented on a global level along with many other "Lean" initiatives. In answer to your question using this Matrix you could come up with a rule like any score equal to or below 8 does not get a look in.