Complex sentence: The opposite is isochronous or synchronous serial communication, where a separate clock signal is transferred, or is retrieved from a self-clocking line code method such as 8B/10B encoding used in Firewire and Manchester code used in Ethernet.
Split into simpler sentences: The opposite is isochronous or synchronous serial communication, where a separate clock signal is transferred. Alternativly the clock signal may be retrieved from a self-clocking line code method such as 8B/10B encoding used in Firewire and Manchester code used in Ethernet.