\begin{definition}[Definition:Apotome/Order]
Let $a, b \in \set {x \in \R_{>0} : x^2 \in \Q}$ be two rationally expressible numbers such that $a > b$.
Let $a - b$ be an apotome.
The '''order''' of $a - b$ is the name of its classification into one of the six categories: first, second, third, fourth, fifth or sixth.
Category:Definitions/Apotome
\end{definition}