location: http://www.openehr.org/releases/AM/latest/docs/AOM2/AOM2.html#_validity_rules
Error VARCN: The parser can check the form of the RootNodeId by regexpr, but it cannot check if the part of this Id which indicates the specialization-depth is true. So that part of the error message should be removed
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I'm not sure of the problem here. The root node id-code defines the specialisation depth, so you are right, it can't be checked, since it is defining it. Probably it should be reworded a bit to clarify this.
I forgot what the problem was, and I have my mind not set on the this part, I suggest you'll wait a few weeks until I come again to it when doing the testing.