(This guide has only just been started)

Conventionally, I put an 'X' at locations in a macro that can't be reached. In
this example snippet a macro returns in command mode after a successful L-LOCATE
(which puts Q in file mode):-

^NC^NL^]^NUX

'X' can never be reached:
either ^NL skips it or ^NU returns before reaching it.
