A Keymix setup with rgba channels and bbox from B, wired for quick stack compositing in the node graph.
Cc is a small stack utility built around a Keymix. It takes two inputs and mixes them on the rgba channels, with the output bounding box taken from input B.
Use it when you need a ready-made Keymix in a stack path without rebuilding the node and its pipe each time. The surrounding dots keep the A and B routes clear so you can drop it into a tree and connect mask and layers with minimal rewiring.
In a comp it behaves like a standard Keymix: foreground and background are combined by the mask, output bounds follow B, and all four rgba channels are included in the mix.