Unfortunately, no. Even Google's own documentation is not particularly clear and leaves room for interpretation. That means that each marketer will probably have their own way of doing things. As long as you're consistent in the naming conventions you use, it won't matter that much. Being consistent with the UTM tags you use is the only way to be able to track them and make use of the data they provide. In addition, some analytics tools use a different system of tags altogether and don't use UTM parameters at all. One of the main risks is wanting to track too many things. You can end up adding UTM tags everywhere, for example naming each button and piece of content with utm_content and utm_term tags. But if you can't make use of the data, there's no need to waste your time tracking it.