The ne plus ultra of hackereditors, it is a programmable text editor with an entire LISP system inside it. Originally written by Richard Stallman at the MITAI Lab, it is described as "an advanced, self-documenting, customizable, extensible, real-time display editor." It has been reimplemented any number of times, by various hackers, and versions exist for major operating systems. Perhaps the most widely used version, also written by Stallman, is called GNU EMACS (or GNUMACS), which runs principally under Unix. It includes facilities to run compilation subprocesses and to send and receive mail. Many hackers spend up to 80 percent of their "tube time" inside it. However, some hackers find EMACS too heavyweight and baroque for their taste, and they expand the name as "Escape Meta Alt Control Shift" to spoof its heavy reliance on keystrokes decorated with "bucky bits." Other spoof expansions include "Eight Megabytes And Constantly Swapping" and "EMACS Makes A Computer Slow."