There's one thing that gives me pause here:

The single most common error is listed as DNS/URI/email format violations. There is absolutely no discussion as to what kinds of violations these break into, nor is there even a discussion as to what the paper thinks the correct formats ought to be. This is unfortunate because the format of these parameters is one thing where specifications often have a view of the world which is completely incongruent with reality. As a simple case, you will sometimes come across documentation that thinks that DNS names cannot start with a digit, which does not match reality at all.