[jolux]

Apple does not use ARM designs, they use certain principles present in the ARM architecture and the ISA.

Wikipedia:

"Companies can also obtain an ARM architectural licence for designing their own CPU cores using the ARM instruction sets. These cores must comply fully with the ARM architecture."

https://en.wikipedia.org/wiki/ARM_architecture#Licensing

[Someone]

That's about the best description I could find, too. It all boils down to what 'comply fully' means.

Given the lego-like structure of the ARM instruction set (the 32-bit variant), with zillions of extensions (Jazelle, DSP instructions, Neon, Thumb, Thumb-2, various revisions of vector floating point instructions) and explicit support for "coprocessors" (https://en.wikipedia.org/wiki/ARM_architecture#Coprocessors), I suspect (based on common sense and nothing else) that the license allows expanding the instruction set and dropping whole modules.

But as I said elsewhere: concrete proof for that is lacking.