Discussions of web standards frequently describe their official definitions as "impenetrable", "confusing" and "messy", almost as if this is self-evident. I can't remember having seen a web specification praised for it's clarity. I'm interested whether the community thinks this is justified.
Which web standard specs have you had cause to refer to and have found inaccessibly defined or written? How would you improve them?
Or, which have you found to be clear and helpful?
Fitting with the theme:
Answers SHOULD cover one specification only.
Constructive criticism, linking to the spec in question and quoting examples are RECOMMENDED.