ARM is as bad at that as Sun. The ARM11, which is an ARMv6, is older than the A5, which is an ARMv7. If you compile something for ARMv7 or later, it will not run on an ARM11. And do not confuse ARMv7 with ARM7 - the later is an ARMv3, or later an ARMv4 or ARMv5.
The ARMv7 family has the A5, A7, A8, A9, and A15. Let's hope it does not get near A32, else things will get even more confusing.