Element bitwidth is best covered as its own special section, as it
is quite involved and applies uniformly across-the-board. SV restricts
-bitwidth polymorphism to default, default/2, default\*2 and 8-bit
-(whilst this seems limiting, the justification is covered in a later
-sub-section).
+bitwidth polymorphism to default, 8-bit, 16-bit and 32-bit.
The effect of setting an element bitwidth is to re-cast each entry
in the register table, and for all memory operations involving