notation

Short definition from Wiktionary

Noun

1. 1
   The act, process, method, or an instance of representing by a system or set of marks, signs, figures, or characters.
2. 2
   A system of characters, symbols, or abbreviated expressions used in an art or science or in mathematics or logic to express technical facts or quantities.
3. 3
   A specific note or piece of information written in such a notation.