As some of you have already discovered, the following item was omitted from the EMME/2 VAX/VMS Supplementary Release Notes for Release 3.0.
The command escape feature ("~!") has been corrected to be compatible with
other EMME/2 implementations. This means that, if only "~!" followed by
zero or more blanks and a carriage return is entered, EMME/2 considers it
to be a null command and returns with "!" immediately. With Release 2 this
would have resulted in the VMS $ prompt appearing and allowed the user
to enter a sequence of VMS commands. With Release 3.0, a sequence of
commands can still be entered but each one must be preceded by "~!".