EINE and ZWEI are two discontinued Emacs-like text editors developed by Daniel Weinreb and Mike McMahon for Lisp machines in the 1970s and 1980s.
[1] In terms of features, its goal was to "do what Stallman's PDP-10 (original) Emacs does".
EINE also made use of the window system of the Lisp machine and was the first Emacs to have a graphical user interface.
ZWEI would eventually become the editor library used for Symbolics' Zmacs (Emacs-like editor), Zmail (mail client), and Converse (message client), which were integrated into the Genera operating system which Symbolics developed for their Lisp machines.
With "zwei" being the German word for "two", "EINE" could be (re-)interpreted as being a reference to the German word for "one" (in the feminine adjectival form, as in "eine Implementierung", "one implementation").