Multiple keymaps can be chained off one keymap using chain-to-keymap. When keymaps are chained to a main keymap, then events handled by the main keymap are passed to the chained keymaps until a chained keymap handles the events. Keymaps can be chained together in an arbitrary acyclic graph.
If next will be used to handle events which are not handled by this keymap. If prefix is TRUE, then next will take precedence over other keymaps already chained to this one.