30 + years in IT, and I remember many tech’s and computer folks talking about DB-9 serial connectors. I needed a d connector for a joystick to Arduino project, and found to my amazement we’ve been calling them wrong for years (ok, so I kinda remember the correct terminology, but the wrong ones were so commonly used). The Joystick uses a DA-15, the Serial a DE-9, and the printer used a DB-25. D stood for the shape of the shell, the second letter (A, B, C, or D) stood for the size, and the numeral, the number of pins or sockets. VGA is a DE-15HD, or High Density.
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http://en.wikipedia.org/wiki/D-subminiature
I don’t even want to get into the “RJ-45” Connector naming issue, but I guess I will. Ethernet does not use a RJ-45 connector. Ethernet uses a 8P8C connector. a RJ-45 is a mechanically-keyed variation of the 8P8C body with an extra tab that prevents it from mating with other connectors, used in telecom applications.
http://en.wikipedia.org/wiki/Registered_jack#RJ45
Hope this sheds some light on issues you never knew were an issue, LOL