Coverage RE usage in Nuke?

[leabum]

I know the Coverage RE can be used to add filtering to unfiltered passes like Render ID. What is the correct workflow for that? Lets say I seperated a color from the RenderID RE with a huekeyer and want to add the filtering to it. What would I do?
Also I would be interested if there are other uses for this pass as well.

[Svetlozar Draganov]

Never used that pass in Nuke but here a tutorial I found on youtube which might be helpful.
https://www.youtube.com/watch?v=Fe6Vazv9_Wg