# EXTRA Field Mapping
The purpose of the 9-bit EXTRA field mapping is to mark individual
-registers (RT, RA, BFA) as either scalat or vector, and to extend
+registers (RT, RA, BFA) as either scalar or vector, and to extend
their numbering from 0..31 in Power ISA v3.0 to 0..127 in SVP64.
Three of the 9 bits may also be used up for a 2nd Predicate (Twin
Predication) leaving a mere 6 bits for qualifying registers. As can
-be seen there is significant pressure on these (and all) SVP64 bits.
+be seen there is significant pressure on these (and in fact all) SVP64 bits.
In Power ISA v3.1 prefixing there are bits which describe and classify
the prefix in a fashion that is independent of the suffix. MLSS for