Subset implementations in hardware are permitted, as long as certain
rules are followed, allowing for full soft-emulation including future
-revisions. Details in the [[svp64/appendix]].
+revisions. Compliancy Subsets exist to ensure minimum levels of binary
+interoperability expectations within certain environments.
+
+## Register files, elements, and Element-width Overrides
+
+In the Upper Compliancy Levels the size of the GPR and FPR Register files are expanded
+from 32 to 128 entries, and the number of CR Fields expanded from CR0-CR7 to CR0-CR127.
+
+```
+ #pragma pack
+ typedef union {
+ uint8_t b[];
+ uint16_t s[];
+ uint32_t i[];
+ uint64_t l[];
+ uint8_t actual_bytes[8];
+ } el_reg_t;
+
+ elreg_t int_regfile[128];
+```
+
+Hardware Architectural note: to avoid a Read-Modify-Write at the register file it is
+strongly recommended to implement byte-level write-enable lines exactly as has been
+implemented in DRAM ICs for many decades. Additionally the predicate mask bit is advised
+to be associated with the element operation and ultimately passed to the register file.
+When element-width is set to 64-bit the relevant predicate mask bit may be repeated
+eight times and pull all eight write-port byte-level lines HIGH. Clearly when element-width
+is set to 8-bit the relevant predicate mask bit corresponds directly with one single
+byte-level write-enable line. It is up to the Hardware Architect to then amortise (merge)
+elements together into both PredicatedSIMD Pipelines as well as simultaneous non-overlapping
+Register File writesto achieve High Performance designs.
## SVP64 encoding features