# Ultra-Embedded Level
-This level is the bare minimum requirements, where everything with the
+This level exists as an entry-level into SVP64, most suited to resource
+constrained soft cores, or Hardware implementations where cost is a
+higher priority than execution speed.
+
+This level sets the bare minimum requirements, where everything with the
exception of the `setvl` instruction may be software-emulated through
JIT Translation or Illegal Instruction traps. SVSTATE joins MSR and PC
as direct peers and must be switched on any context-switch (Trap or
* SVSTATE **must** also be saved/restored to/from SVSRR1
Any implementation that implements Hypervisor Mode must also
-correspondingly follow the Power ISA Spec for HSRR0 and HSRR1,
-and must save/restore SVSTATE to/from HSVSRR1.
+correspondingly follow the Power ISA Spec guidelines for HSRR0 and HSRR1,
+and must save/restore SVSTATE to/from HSVSRR1 in all circumstances
+involving save/restore to/from HSRR0 and HSRR1.
+
+Illegal Instruction Trap **must** be raised on:
+
+* Any SV instructions not implemented
+* any unimplemented SV Context SPRs read or written
+* all unimplemented uses of the SVP64 Prefix
+
+Implementors are free and clear to implement any other features of
+SVP64 however only by meeting all of the mandatory requirements above
+will Compliance with the Ultra-Embedded Level be achieved.