(many Vector ISAs have operations which, due to higher internal
accuracy or other complexity, must be effectively atomic for
the full Vector operation's duration, adversely affecting interrupt
- response latency)
+ response latency, or be abandoned and started again)
* Augments ("tags") existing instructions, providing Vectorisation
"context" rather than adding new instructions.
* Strictly does not interfere with or alter the non-Scalable Power ISA