The M1 connector is also known as M-1, EVC or P&D connector. It's also known as an InFocus or Proxima projector adapter, among the many brands that included an M1 connector.
Do not confuse the M1 connector with a DVI connector. The M1 connector is wider since it has 30 holes (or pins if male) on three rows of ten holes plus four holes and a wider horizontal hole (or pin if male)
The M1 connector is used on some projectors to allow for either VGA, DVI, HDMI component video input plus USB power.