Verify uses for new layers

I just wanted to verify the uses for the new layers I’m seeing in kicad.

Are the F.CrtYd and B.CrtYd layers for defining a keepout area around a component?

Are the F.Fab and B.Fab for creating assembly drawings that show more physical details of the component that won’t appear on the silkscreen?

What does the margin layer do? The tooltip says “Board’s edge setback outline”. Is that so you can have a larger PCB but restrict the wiring and components to a smaller area within the PCB?


Courtyard, Something used by some IPC standard.

I am not quite sure what the margin or fab layer do.