Some notation regarding "::"

Question

I'm reading through some geometry proofs, and I can see something like

$AB^2:PM\times EB::BC^2\ :CD\times PQ$

So I understand that $A:B$ is equivalent to $\frac{A}{B}$, but what does the $::$ mean?

Answer 1

HINT

$$ A:B :: C:D \equiv \implies \dfrac{A}{B} = \dfrac{C}{D} $$

The notation is called proportion.

$A$ is to $B$ as $C$ is to $D$.

Answer 2

Assuming it says $CD \times PQ$ instead of $CD \times : PQ$, I believe the above statement is equivalent to \begin{align*} \frac{AB^2}{PM \times EB} = \frac{BC^2}{CD \times PQ} \end{align*}