Note that 7 options are needed (not 6) because the 7th option allows predicate masking to be encoded within the swizzle immediate.
For example this allows "W..Y" to be specified, "copy W to position X,
and Y to position W, leave the other two positions Y and Z unaltered"
+
+# RM Mode Concept:
+
+MVRM-2P-2S1D:
+
+| Field Name | Field bits | Description |
+|------------|------------|----------------------------|
+| Rdest_EXTRA2 | `10:11` | extends Rdest (R\*\_EXTRA2 Encoding) |
+| Rsrc_EXTRA2 | `12:13` | extends Rsrc (R\*\_EXTRA2 Encoding) |
+| src_SUBVL | `14:15` | SUBVL for Source |
+| MASK_SRC | `16:18` | Execution Mask for Source |
+
+The inclusion of a separate src SUBVL would allow either
+`sv.mv.swiz RT.vecN RA.vecN` to mean contiguous sequential copy
+or it could mean zip/unzip (pack/unpack).