ISO is an organization. OSI is a model.

Edit: there are also definitely more than four “layers” (standard handoff points).

• Physical involves the media and transmission format (e.g. EMF, waveform, etc)

• data link involves multiplexing and addressing on the local segment

• Network involves beyond-segment addressing

• Transport involves standard endpoint communication methods (tcp/udp)

Are you implying this is where everything ends?

What about application level multiplexing (sockets)?