I read carefully the slides  "What do YOU want UML to be?". I would like to
extend elements defined in L0 or LM (not the UML superstructure) but don't know
where/how to load the resource defining these levels.
I also read the tutorial  "Applying UML Profile for Domain Metamodel" but he
loads the whole superstructure UML.
In a last attempt, I imported the uml plugin fragment... But it seems to
me that it is not the good way...