@whitequark I have seen "MIIM" maybe once or twice in my lifetime. Most I've seen, people just call it "c45_read" / "c22_read" and the like.
E.g. this bonanza: https://patchwork.kernel.org/project/netdevbpf/patch/20210331141755.126178-3-danilokrummrich@dk-develop.de/
Everything is MDIO.