I’ve created a Case Entry Kinetic Layer. In the Layer under the related information section, I’ve created a new Serial Number text box.
In this box I want to prepopulate it with the serial number, which for us is Sales Order + Line + Release.
I know the data I need to populate is
(HDCase.OrderNum - HDCase.OrderLine - HDCase.OrderRelNum)
How do I do this in Application Studio?
You’ll need to bind that textbox to a dataview.column binding (if it is not already).
Then, you’ll need event with a row-update where you set the value of the above dataview.column to an expression of something like
"{HDCase.OrderNum}" + "-" + "{HDCase.OrderLine}" + "-" + "{HDCase.OrderRelNum}"
I may not be 100% correct on the expression syntax. No matter how many times I do it, I have to play around to find the right format 
The last thing you need to figure out is when/how to trigger the above event.