Component libraries can be identified with the file extension .cml. Each component in a library is aware of the symbol name and library name of its constituent symbols. The components can each contain several Schematic symbol ‘gates’, and a number of PCB footprints, each with its own symbol. For example, a component might have 3x NAND gates and a power gate for use in the Schematic design, a DIL and an SMD footprint for use in PCB, all assigned to it.
The diagram below shows how the component will access both the Schematic symbol library and the PCB symbol library as required in the relevant design editor.
How can I use the Library Manager?
How can I manage embedded libraries?
Video tutorial: Library Structure & Library Manager