The Macintosh Keyboard Layout owes a lot more to the Apple II than you might think. This is because the first comptuer Apple released with an ADB keyboard was the Apple IIGS; the Mac SE came later and used it. Or perhaps the ADB layout was designed with both models in mind. Either way, the Mac keyboard and the Apple II keyboard share a common history.
The Apple IIe was the most popular Apple II, and its keyboard had two Apple keys on either side of the spacebar: the Open Apple key (on the left) and the Solid Apple key (on the right). They were never called "Light Apple" and "Dark Apple" by the industry, mainly because Apple used both white and black silkscreening on the beige keys back then, depending on the model and what subcontractor delivered the keyboards that year.
Interestingly, the Open Apple and Solid Apple keys were electrically identical to the two buttons on the standard Apple II joystick. If you had a very old Apple II (such as an Apple II+) which lacked these keys and you needed to press "Open Apple Q," you'd press one of the joystick buttons and Q at the same time.
Back to the IIGS/Mac SE. When the "new" ADB keyboard came out, the Open Apple key became the Apple/Shamrock key. The Solid Apple key became the Option Key. Needless to say, this was very annoying when you played a pinball game on a IIGS where the left and right flipper buttons were the Open Apple/Solid Apple keys, and now what used to be the right Apple key (Solid Apple) was now on the left of the keyboard in the form of Option.
So anyway, when you hear a Mac user (and I have a few Macs myself, too) say "Open Apple Q" to quit, that person may be a very old Apple II user. If they call the Option key the Solid Apple key, then you know it for sure.
