It is important to appreciate that *only* the main loop VL
is Vertical-First: the SUBVL loop is not. This makes sense
from the perspective that the Swizzle Move is a group of
-moves, but is still a single instruction. Vertical-First
-only performing one of the *sub*-elements at a time would
-break that expectation. The exceptions to this, explained
+moves, but is still a single instruction that happens to take
+vec2/3/4 as operands. Vertical-First
+only performing one of the *sub*-elements at a time rather
+than operating on the entire vec2/3/4 together would
+violate that expectation. The exceptions to this, explained
later, are when Pack/Unpack is enabled.
**Effect of Saturation on Vectorised Swizzle**