instructions, these make no sense to Vectorise.
However, it is really quite important to not be tempted to conclude that
-just because these instructions are un-vectoriseable, the opcode space
+just because these instructions are un-vectoriseable, the Prefix opcode space
must be free for reiterpretation and use for other purposes. This would
be a serious mistake because a future revision of the specification
-might *retire* the Scalar instruction, replace it with another.
+might *retire* the Scalar instruction, and, worse, replace it with another.
Again this comes down to being quite strict about the rules: only Scalar
instructions get Vectorised: there are *no* actual explicit Vector
instructions.