I have to reflect on "classic" Behavior and also on traits. For Behavior I  
can use

	aTraitOrBehavior canUnderstand: aSelector

and be assured that at another point in time, in the same image instances  
of aTraitOrBehavior will respond to aSelector.

What query must be used for Trait and TraitComposition, in the same sense,  
i.e. users of this traits / composition will definitely respond to  
aSelector.

And what query must be used in analogue to #isBehavior when  
aTraitOrBehavior is Trait or a TraitComposition. I have to avoid DNU in  
images without traits.

I can find out many details by myself but would like to check against an  
expert opinion. Thank you in advance.

/Klaus