I see the "D" this, the "O" that and the "X's", "SLT", ALPHA and more alphabetical, numerical designations for cameras from a variety of manufacturers. How many designations does Nikon have? Olympus had the "E" series starting, I think, with the E-500, E-1 and E-620 and now the "OM" series. Enough to give one a headache.
With Sony coming out with new mounts quicker than we get new US presidents, I would be overwhelmed. But Canon is pretty straightforward, thankfully.