  << ^ N D - I N I T I A T E   S U B R O U T I N E   C A L L >>

 In fact this pseudo simply pushes a return link (to the 3rd character
following in the macro (which need not exist but the next 2 must)) but it is
almost always used to call another macro as a subroutine, by following it with
a branch to another macro. The called macro (or any other macro it branches to)
can return to the next character in the calling macro by using the ^NU pseudo
('H CN-U'). The called macro should not simply branch back to the calling one,
because whereas the stack is large it is finite and if it fills up an error
condition is signalled (bell rings and macro is quitted out of, also the stack
is thrown away).
 Example
 See ^NL ('H CN-L') for an example.
