I had a boat with both AC & DC sockets, but we had the normal socket for both and the label plates showed you which was which. I don't think that solution is acceptable for the wider marketplace, the plugs should probably be physically distinct. Maybe USB-C is the solution, though I don't know how long the cables can be.
http://electronics.howstuffworks.com/gadgets/automotive/dc-a...
(My late dad was an industrial engineer for a company that manufactured electric generators, so this issue immediately jumped into my mind when I saw the comment I replied to. The difference between AC power and DC power was dinner-table conversation in my home when I was growing up.) Does anyone think that my comment above was in any way harmful to the community or to the discussion here?