</pre>
</code>
+# Is this like MISA? <a name="misa"></a>
+
+No.
+
+* MISA's space is entirely taken up (and running out).
+* There is no allocation (provision) for custom extensions.
+* MISA switches on and off entire extensions: ISAMUX/NS may be used to switch multiple opcodes (present and future), to alternate meanings.
+* MISA is WARL and is inaccessible from everything but M-Mode (not even readable).
+
+MISA is therefore wholly unsuited to U-Mode usage; ISANS is specifically permitted to be called by userspace to switch (with no stalling) between namespaces, repeatedly and in quick succession.
+
# What happens if this scheme is not adopted? Why is it better than leaving things well alone? <a name="lassezfaire"></a>
At the first sign of an emergency non-backwards compatible and unavoidable