Let $A$ = {2, 3, 4, 7} and $B$ = {1, 2, 3, ..., 12}. Define $aSb$ if and only if $a | b$

Question

I just started learning about set relations and there is a question in the book

Let $A$ = {2, 3, 4, 7} and $B$ = {1, 2, 3, ..., 12}. Define $aSb$ if and only if $a | b$. Use the roster method to describe $S$

It seems to me that I need to find instances of $a$ related $b$ when the criteria $a | b$ is met, but the only time I have seen the bar ($|$)is to indicate "such that" in set-builder notation(example, ${ n | n > 0 } = {1,2,3,...}$) and in that context, the question doesn't make sense to me.

Is it asking for ordered pairs where $a$ related to $b$ such that $a$ such that $b$?

Can someone tell me how to interpret this question and solve it?

Answer 1

$a\mid b$ means "$a$ divides $b$". So $4S12$ but $7\not S 5$.