Question about an arrow diagram

Question

My question is this, I understand how to find the S diagram, once I find the cartesian products and do x < y which explain all the arrows in the S diagram. However, I do not understand the T diagram or what T means or where they get the (2,1), (2,5) in this example. Here is a screenshot from my textbook example.

The example in the book is,

Let A = {1,2,3} and B = {1,3.5} and define relations S and T from A to B as follows:

For all (x,y) ∈ A x B draw arrow diagrams for S and T.

I just don't know what T is and how the example gets {(2,1), (2,5)}.

Answer 1

The only guess I can make for the relation T is to make the target of T not have the same value as the starting value. That would make T not well-defined as a function. The other possibility would be that T includes all relations going from A to B, making the answer above a subset of that relation.