MHL is connection agnostic (i.e., not tied to a specific type of hardware
connector). The first implementations dual-purpose the most popular mobile
connection (micro USB <http://en.wikipedia.org/wiki/Micro_USB>) and the
most popular HDTV connection (HDMI <http://en.wikipedia.org/wiki/HDMI>).
Other than the connectors being used, no USB nor HDMI technology is being
used. It is exclusively MHL signalling through the connectors and over the
cable. Other proprietary and custom connections are also allowed.