Using Business Rules inside maps

Not by design but you can create a .Net helper class to execute Business Rules and then use it’s methods from your map via scripting functoid (external .Net assembly).

There may be some gotchas if you want to send the whole source document or it’s node-like parts into the rules. Same for returning multiple result objects. But still possible with some .Net scripting involved. You will not be able to assign values into resulting document directly within a rule though.