https://github.com/ARM-software/abi-aa/blob/main/sysvabi64/sysvabi64.rst#about-this-document (emphases added):
Q-o-I
Quality of Implementation – a quality, behavior, functionality, or mechanism not required by this standard, but which might be provided by systems conforming to it. Q-o-I is often used to describe the toolchain-specific means by which a standard requirement is met.
It seems that "standard" needs to be "document" in the text above.
Also: the name of the document is "System V ABI for the Arm® 64-bit Architecture (AArch64)". However, in the text of the document the document is referred as "ABI for the Arm 64-bit Architecture". Is it a typo? Why not using a unified document name?
Also: it says:
The ABI for the Arm 64-bit Architecture uses the following terms and abbreviations.
...
Q-o-I
Searching for "Q-o-I" produces no results. Meaning that term "Q-o-I" is not used. Confused.