Zmacs was one of the many variants of the Emacs text editor that runs on the Symbolics Lisp machine. It was based on the Zwei programming substrate, which stood for "Zwei Was Eine Initially"; Zwei was a collection of routines which could be used to easily implement other programs, like the Symbolics mail program, Zmail- Eine stood for "Eine is not Emacs". Eine and zwei are German for one and two respectively.