I agree with you, mostly. But if we're going to nitpick about the acronym, it's only the "R" bit that refers to the mirror/prism, the "SL" bit is separate to t

I agree with you, mostly. But if we're going to nitpick about the acronym, it's only the "R" bit that refers to the mirror/prism, the "SL" bit is separate to that. A "plain old digital camera" is an example of a Digital Single Lens camera. It just doesn't do the "Reflex" trick of sending the image to the viewfinder(/autofocus/lightsensor) with a mirror/prism. (I'm out of my camera historical terminology depth here, but I'm assuming there "SL" bit made it onto the common use SLR acronym to differentiate from cameras where the viewfinder had it's own lens, and didn't use the same "single" lens that the optical path to the film used.)