Render priority

I’ve never quite understood the point of this column in the render list as there doesn’t seem any way to change it, however I now have a render node that has come up with a priority of 0 and refuses to render.
Replacing it fixes, but very odd!

If two render nodes share any part of the same setup, they’ll share the render priority. If you have multiple isolated render setups in a single batch you can change the priority of when they render.