image editor layers?

Does anyone know what the drop down menu that simply has numbers 0 and up is for in the image editor window when render output is selected; are these layers ? how would you utilize them.

Wrong forum!

But to answer your question, they’re renderbuffers. 1st choose a slot, then hit render. Then select another slot, change something in your scene, hit render. Now you can compare renders. Use j key to cycle through used slots.

Thanks, this is a cool feature!