CAN BUS and CAN Protocols
It simply means that someone picked very bad signal names for the 9 pin connector, in order to confuse everyone. From what I can tell:


C "J1939+" would be CANH, a signal used in CAN.
D "J1939-" would be  CANL, a signal used in CAN.
E shield 
F "J1708+" would be  B+, a signal used in RS485.
G "J1708-" would be  A-, a signal used in RS485.


As far as I can tell, H and J are OEM specific signals.

Apparently "ODB type 2" connectors may have either RS485 or CAN on the same pins, F and G.