This was defined during the shift from IBM 9 pin VGA to the VESA DDC 15 pin connector. On the IBM 9 pin connector, pin 9 was 12V, but never specified the maximum current.

Attaching a VGA extension cord to the projector's VGA port allows this Thinkpad to successfully use the projector.<BR><BR>The projector's vga pinout appears to have a ~40% normal height pin #6 on ...

VGA, DVI, and HDMI ports use Display Data Channel (DDC) to communicate with connected displays. This allows displays to be plug and play. However, DDC is based on I2C, which is used in all kinds of… ...

For example, the analog VGA monitor interface uses a D-sub 15-pin plug and socket. Also called "DB connectors" and "D-subs," they come in 9, 15, 25, 37 and 50 pin varieties.