[OH3] Start Level usage for rules?

Where could I find information about the correct usage of Start Level in a System started triggered rule?
Especially which level to use for a rule that is supposed to run after the items are created.

I assume we are lacking documentation at the moment. You have to enter 20 to trigger StartLevel based rules:


I do use ECMA scripts located in /etc/openhab/automation/…

Even when I am force them by file name rule.sl20.js to Start at SL20 the file based DSL *.rules are starting before.

How can I change this?