That is all reasonable, but weâre narrowly talking about entity names (such as node templates, property names, requirement names, etc.), not the values for those entities.
But these are also values that are often validated by the parser. E.g. if you give a "bad" name to a requirement it should cause an error if it can't be matched at the node type or node template.
I'm really confused as to where this is all going. Typos can happen anywhere in any computer language, whether it's restricted to English's [a-zA-Z] or all of Unicode.
I'm sorry Chris and Adam, but I think this issue is exhausted as far as I'm concerned. I am trying to get from you some specific problem with the current lack of restriction and have not heard anything that looks specific to me. On the other hand, I've raised a few reasons why you would want to keep it unrestricted -- visual IDEs, separation between design and runtime elements, TOSCA generated from external systems, future uses that we don't even know about, the arbitrariness of picking just any set of rules (XML? why?) -- and have not gotten any arguments against them.