My response was poorly worded.
Yup, is the answer, those numbers correspond to the unions only.
Once the unions are added under your DT, two of them will accept schedule 40 PVC at 1”, or whatever standard stuff you want.
The return would accept 3/4” schedule 40, but I used a 3/4” to 1” schedule 40 adapter, so that all pipes are then 1”.
All three gate valves are standard 1”.
You don’t need one on the return, I put one there just in case there was some reason to lock off all three.
But the other 2 must have gates for fine tuning your flow.
Hope that’s clearer.