+ENVIRONMENT: A Muddle object which specifies a particular set of
+variable bindings. An ENVIRONMENT is normally cumulatively built up
+as the control stack of a program builds and ATOMs are bound. The
+ENVIRONMENT actually corresponds to a particular point on the control
+stack. A program may have an object evaluated in an ENVIRONMENT
+specifying the current state of another running program. The effect
+is as if the latter program had evaluated the object.
+
+ESP: A debugging system for assembly-language programs.
+
+EVAL: A build-in Muddle function that evaluated an object and returns
+the value of that object
+
+FIX: A Muddle object that is an integer.
+
+FLOAT: A Muddle object that is a floating-point number.
+
+FORM: A list of Muddle objects which is evaluated by applying the
+first element (some function) to the rest of the elements (its
+arguments). "Execution" in Muddle generally refers to the evaluation
+of a FORM. The evaluation of that FORM will often require the
+evaluation of other FORMs (the arguments to the function or FORMs in
+the body of the function ).
+
+FRAMES: A pre-loaded function that shows the programmer a printed
+representation of the control stack of the current program.
+
+IMED: An editor for Muddle objects that works by outputting an object
+to the IMLAC where the local editing functions are used.
+
+IMLAC: A minicomputer with a keyboard and CRT display used as an
+intelligent terminal.
+
+ITS: A general-purpose time-sharing operating system developed by the
+Artificial Intelligence Laboratory at M.I.T.
+
+LVAL: A built-in Muddle function that returns the local value of a
+given ATOM. The local value is that which was last bound to the ATOM
+In the current ENVIRONMENT.
+
+Muddle: An applicative programming language used to implement MEND.
+
+MEND: Muddle Executor, aNalyzer, and Debugger. The subject of this
+report.
+
+MSC: Multi-Screen Console program for an IMLAC. This gives the IMLAC
+used as a terminal a capability for having several virtual screens
+that may be accessed and displayed independently.
+
+MSTACK: A structure that MEND builds to contain a representation of
+the control stack of the application program.
+
+MUMBLE: An early debugging aid for Muddle programs providing a
+display of the application program's control stack.
+
+PPRINT: A pre-loaded Muddle function that "Pretty-PRINTs" an object
+in a format which indicates the positions of its elements and
+sub-elements in the tree hierarchy.
+
+PRINTTYPE: A built-in Muddle function allowing the programmer to
+specify exactly how any particular type of object should be printed.
+May be used to output characters that will be interpreted as special
+commands on input. See READ-TABLE.
+
+PROG: A built-in Muddle function used for sequential execution of
+Muddle objects (generally FORMs). This function provides for binding
+of ATOMs to be used within the PROG's scope and then evaluates each
+of the objects in its body, usually in order. It is possible,
+however, to alter the flow of control by branching forward or
+backward to another part of the PROG body. See REPEAT.
+
+READ-TABLE: A table that may be set up in Muddle to specify how any
+character should be treated on input. See PRINTTYPE.
+
+REPEAT: Like PROG except that when the end of the body of objects is
+reached, control returns to the beginning.
+
+SSV: The normally used IMLAC console program. See MSC.
+
+UNDO: A Muddle program that stores information about the execution of
+an application program so that the execution may be backed up to some
+previous point at any time.
+