| Field Name | Field bits | Description |
|------------|------------|----------------------------------------|
| MASKMODE | `0` | Execution (predication) Mask Kind |
-| MASK | `1:3` | Execution Mask |
+| MASK | `1:3` | Execution Mask |
+| SUBVL | `8:9` | Sub-vector length |
+
+The following fields are optional or encoded differently depending
+on context after decoding of the Scalar suffix:
+
+| Field Name | Field bits | Description |
+|------------|------------|----------------------------------------|
| ELWIDTH | `4:5` | Element Width |
| ELWIDTH_SRC | `6:7` | Element Width for Source |
-| SUBVL | `8:9` | Sub-vector length |
+| EXTRA | `10:18` | Register Extra encoding |
| MODE | `19:23` | changes Vector behaviour |
+
* MODE changes the behaviour of the SV operation (result saturation, mapreduce)
* SUBVL groups elements together into vec2, vec3, vec4 for use in 3D and Audio/Video DSP work
* ELWIDTH and ELWIDTH_SRC overrides the instruction's destination and source operand width
* MASK (and MASK_SRC) and MASKMODE provide predication (two types of sources: scalar INT and Vector CR).
+* Bits 10 to 18 (EXTRA) are further decoded depending on the RM category for the instruction, which is determined only by decoding the Scalar 32 bit suffix.
-Bits 10 to 18 are further decoded depending on RM category for the instruction.
Similar to OpenPOWER `X-Form` etc. these are given designations, such as `RM-1P-3S1D` which indicates for this example that the operation is to be single-predicated and that there are 3 source operand EXTRA tags and one destination operand tag.
Note that if ELWIDTH != ELWIDTH_SRC this may result in reduced performance or increased latency in some implementations due to lane-crossing.