| Rsrc1\_EXTRA2 | `12:13` | extends Rsrc1 (R\*\_EXTRA2 Encoding) |
| Rsrc2\_EXTRA2 | `14:15` | extends Rsrc2 (R\*\_EXTRA2 Encoding) |
| Rsrc3\_EXTRA2 | `16:17` | extends Rsrc3 (R\*\_EXTRA2 Encoding) |
-| EXTRA2_MODE | `18` | used by `msubed` and `madded` for RS |
+| EXTRA2_MODE | `18` | used by `divmod2du` and `madded` for RS |
+
+These are for 3 operand in and either 1 or 2 out instructions.
+3-in 1-out includes `madd RT,RA,RB,RC`. (DRAFT) instructions
+such as `madded` have an implicit second destination, RS, the
+selection of which is determined by bit 18.
## RM-1P-2S1D