This post covers OPA Decisions, as well as leveraging List of Values in a Form. It also discusses different form presentations e.g. Order Entry Person has a different form to the Approver. It also highlights some simple tips around OCI Process Automation. I don't like referring to the service as OPA as that means grandfather in German, but forgive me, if I sometimes do so.
You will be happy to know I'm sticking with the simple order approval example from the first OPA post -
Creating and Using Decisions
Using LOVs / Multiple Form Presentations
I will do the same with the Product LOV, but first I have to create a BusinessType based on the LOV.