  << ^ N U - S U B R O U T I N E   R E T U R N >>

 In fact this pseudo simply pops a return link (which consists of macro-id and
position in macro) from the stack. Normally used to return from a macro which
has been called as a subroutine (or branched to by one that has been so
called).
 If the stack is empty, i.e. the macro has been invoked directly from the
keyboard (or command source) or has been branched to by one that was, then ^NU
just exits from the macro. This is definitely not an error condition. Thus it
is good practice to write all your macros ending in ^NU or using it instead of
the less useful ^NX even if you don't initially intend to call them from other
macros, because the time might come when you want to.
 Example
 The last example ^NA in the help file for ^NC (type 'H CN-C') is in fact
callable as a subroutine, as it uses ^NU to exit.
