+Options
+=======
+
+* SVPrefix augments the main Specification_
+* SVPregix operates independently, without the VL (and MVL) CSRs (in any priv level)
+* SVPrefix operates independently, without the SUBVL CSRs (in any priv level)
+* SVPrefix operates independently, with no support for VL (or MVL) overrides in the 64 bit instruction format either (VLtyp=0)
+* SVPrefix operates independently, with no support for svlen (SUBVL) overrides in either the 48 or 64 bit instruction format either (svlen=0).
+
+All permutations of the above options are permitted, and in the UNIX platform must raise illegal instruction exceptions on implementations that do not support them.
+
+The options
+
+If required, the STATE, VL, MVL and SUBVL CSRs all operate according to the main specification: hypothetically an implementor could choose not to support setting of VL, MVL or SUBVL (only allowing them to be set to a value of 1). STATE would then not be required either.
+
+If support for SUBVL is to be provided, storing of the sub-vector offsets and SUBVL itself (and context switching of the same) in the STATE CSRs are mandatory.
+
+If support for VL is to be provided, storing of VL, MVL and the dest and src offsets (and context switching of the same) in the STATE CSRs are mandatory.
+