Purpose of selecting joint end type in valve data input

I want to know why there is an option to select valves joint end type as Weldneck and Slip-on.

In my opinion, the joint end connection like this is associated with flanges to pipe connection only, so what purpose does it serves to select weldneck or slip-on as joint end type in valve data input.

Am I incorrect asking this question? Is there any information that I am missing?

Thank you