change all [GPR to FPR conversion instructions](#GPR-to-FPR-conversions)
to instead write `+0.0` if `RA` is register `0`, allowing clearing FPRs.
-| 0-5 | 6-10 | 11-24 | 2t-30 | 31 |
-|========|======|=======|=======|=====|
+| 0-5 | 6-10 | 11-25 | 26-30 | 31 |
+|--------|------|-------|-------|-----|
| Major | FRT | FI | XO | FI0 |
The above fits reasonably well with Minor 19 and follows the
-pattern shown by `addpcis`. If four columns are used it is possible
-to gain 2 extra bits to make FI up to 16 bits. Less than 14 is
-not recommended as it truncates the mantissa range.
+pattern shown by `addpcis`. 15 bits of FI fit into bits 11 to 25,
+the top bit FI0 (MSB0 numbered 0) makes 16.
## FPR to GPR conversions