This is conceptually quite easy to keep in mind that a Vertical-First
instruction does one element at a time, and when SUBVL is set,
that "element" in essence becomes a vec2/3/4.
+
+# Swizzle and Pack/Unpack
+
+These are both so weird it's best to just read the pages in full
+and pay attention: [[sv/mv.swizzle]] and [[sv/mv.vec]].
+Swizzle Moves only engage with vec2/3/4, *reordering* the copying
+based on an immediate supplied by the instruction. The fun
+comes when Pack/Unpack are enabled, and it is really important
+to be aware how the Arrays of vec2/3/4 become re-ordered
+*and swizzled at the same time*.