When creating detection rules such as Business Transaction, Service Endpoint or Backend Detection rules, the priorities are always evaluated as highest number first.
As a top tip, always set these priorities in increments of 5, or even 10! This way, if later you choose to add a new rule between existing ones, it will be easy to do.
You won't have to reprioritise your rules to make room, but you may have to if you'd chosen to increment by 1.
