A Notation is a set of well-defined rules for representing quantities and operations with symbols.
See also Arrow Notation, Chained Arrow Notation, Circle Notation, Clebsch-Aronhold Notation, Conway's Knot Notation, Dowker Notation, Down Arrow Notation, Petrov Notation, Scientific Notation, Steinhaus-Moser Notation
References
Cajori, F. A History of Mathematical Notations, Vols. 1-2. New York: Dover, 1993.
Miller, J. ``Earliest Uses of Various Mathematical Symbols.''
http://members.aol.com/jeff570/mathsym.html.
Miller, J. ``Earliest Uses of Some of the Words of Mathematics.''
http://members.aol.com/jeff570/mathword.html.