| 0-5 | 6 | 7 | 8-31 | 32-3 | Description |
|-----|---|---|-------|------|---------------------------|
| PO | 0 | 0 | !zero | 0b11 | SVP64Single:EXT248-263, or `RESERVED3` |
+| PO | 0 | 0 | 0000 | 0b11 | EXT248-263 or `RESERVED2` |
| PO | 0 | 1 | nnnn | 0b11 | SVP64:EXT248-263 |
-| PO | 1 | 0 | 0000 | 0b11 | EXT248-263 or `RESERVED2` |
| PO | 1 | 0 | !zero | nn | SVP64Single:EXT000-063 or `RESERVED4` |
| PO | 1 | 1 | nnnn | nn | SVP64:EXT000-063 |
|-------|-----------|--------------|-----------|---------------|
| 64bit | fishmv | 0x24000000 | 0x12345678| scalar EXT2nn |
| 64bit | ss.fishmv | 0x24!zero | 0x12345678| scalar SVP64Single:EXT2nn |
-| 64bit | sv.fishmv | 0x26nnnnnn | 0x12345678| vector SVP64:EXT2nn |
+| 64bit | sv.fishmv | 0x25nnnnnn | 0x12345678| vector SVP64:EXT2nn |
Here the encodings are the same, 0x12345678 means the same thing in
all cases. Anything other than this risks either damage (truncation
|-------|-----------|--------------|-----------|---------------|
| 64bit | mtmsr2 | 0x24000000 | 0x12345678| scalar EXT2nn |
| 64bit | ss.mtmsr2 | 0x24!zero | 0x12345678| scalar SVP64Single:EXT2nn |
-| 64bit | sv.mtmsr2 | 0x26nnnnnn | 0x12345678| vector SVP64:EXT2nn |
+| 64bit | sv.mtmsr2 | 0x25nnnnnn | 0x12345678| vector SVP64:EXT2nn |
For a given hypothetical `mtmsr2` which is inherently Unvectoriseable
whilst it may be put into the scalar EXT2nn space it may **not** be
|-------|-----------|--------------|-----------|---------------|
| 64bit | unallocated | 0x24000000 | 0x12345678| scalar EXT2nn |
| 64bit | ss.fishmv | 0x24!zero | 0x12345678| scalar SVP64Single:EXT2nn |
-| 64bit | sv.fishmv | 0x26nnnnnn | 0x12345678| vector SVP64:EXT2nn |
+| 64bit | sv.fishmv | 0x25nnnnnn | 0x12345678| vector SVP64:EXT2nn |
Both of these Simple-V operations are illegally-allocated. The fact that
there does not exist a scalar "Defined Word" (even for EXT200-263) - the