Domonkos, well, at least some requirements, anyway :). Remember that Stephen Mellor is an original signatory of the Agile Manifesto for Software Development.
He expressed disappointment that the industry focused on 3GL Agile instead of Model Driven Agile here: http://www.softed.com/resources/docs/stephen%20mellor%20agile%20manifesto%2010%20years%20on.pdf
I suppose the answer to my question is “it depends” and you really cannot validate a model just by looking at it. You have to know the context and the purpose of the model. The insight can be gained face-to-face, from model notes, requirements, etc.
Cort, it would be great if you could give us a little blurb on the purpose of a particular snippet in future postings. It will help me learn how to do that for my own models.