We are all aware of the complexity of the UML metamodel. To facilitate its learning to UML newbies (and not so newbies!), EmpowerTec offers a free UML metamodel viewer that allows to:

• Browse the metaclasses of the UML2 metamodel specification
• See their relationships by dragging them to a class diagram to see in a graphical way their attributes and the associations linking them

See a screenshot of this metamodel viewer (taken directly from Empowertec’s blog )

and if you like this tool don’t forget to take a look at their other tool Oclarity tool
(a productivity environment for OCL), recently featured in this same blog.