normal SVP64 `sz=1` behaviour, where *only* a zero is put in
place of masked-out predicate bits.
* **sz=0** When `sz=0` skipping occurs as usual, but unlike all
- other SVP64 behaviour, there are certain exceptional
- special circunstances where CTR
+ other SVP64 behaviour which entirely skips an element with
+ no related side-effects at all, there are certain
+ special circumstances where CTR
may be decremented. See CTR-test Mode, below.
* **ALL** when set, all branch conditional tests must pass in order for
the branch to succeed. When clear, it is the first sequentially