Definition:Plane Number/Similar Numbers

Definition
Let $m$ and $n$ be plane numbers.

Let:
 * $m = p_1 \times p_2$ where $p_1 \le p_2$
 * $n = q_1 \times q_2$ where $q_1 \le q_2$

Then $m$ and $n$ are similar iff:
 * $p_1 : q_1 = p_2 : q_2$