* (x)ePCVBLK (a copy of the sub-execution Program Counter, that is relative
to the start of the current VBLOCK Group, set on a trap).
-* (x) eSTATE (useful for saving and restoring during context switch,
+* (x)eSTATE (useful for saving and restoring during context switch,
and for providing fast transitions)
The u/m/s CSRs are treated and handled exactly like their (x)epc
The main effect of SUBVL is that predication bits are applied per
**group**, rather than by individual element. Legal values are 1 to 4.
+Illegal values raise an exception.
## STATE