Hi Ulic, Thanks for the feedback! Remember I'm fairly new to NLP, so most of what I wrote above was extracted/paraphrased from Michael Carroll's post (with my additional suggestion that we define a level of sub-units of "patterns", tentatively named "procedures"). I haven't read "Turtles All The Way Down", but have now ordered it! The terms "source" and "function" were extracted from Michael's post, but my take on it is - - "source" is the name of the person who was modelled (Milton Erickson, in Michael's example of the Milton Model) - "function" is the purpose of the pattern, what it is designed to do. Referring to your recent posts about defining a sensory-based description of what a pattern should achieve, I'd say "function" is a word or short phrase that summarises that description. So, in the case of the Meta Model, the patterns came from different sources, but have a common function - to recover the deletions/distortions in the client's language. I'm not sure I understand your last question, could you give an example? Do you mean that in some models certain patterns should be used in a certain order - run Pattern A, then Pattern B, if that doesn't work try Pattern C? If so, that's what I was trying to get at when I asked whether a model is more than its constituent patterns - i.e. are there some instructions at the top-level of the model which tell you when/how to use one, or several, of its patterns (and in what order), in different contexts? Cheers, Jon