trusted property

I'm not sure what the use case is for exposing a "trusted" property to  
normal scripts. It also seems rather draconian to say that "All other  
untrusted events must behave as if the Event.preventDefault() method  
had been called on that event". This comes right after a sentence  
saying "should not trigger default actions". So is this a "should" or  
a "must" requirement for an implementor?

(  
http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html#trusted-events  
)

Also, it may need to say that setting properties directly on the event  
object should change event.trusted to false? E.g. some browsers let me  
set event.keyCode for a key event. Having done that the event is  
presumably no longer "trusted"?

-- 
Hallvord R. M. Steen
Core tester, Opera Software