I've been playing Hanabi for a while now with a few groups of people.
Recently, we realized that there was a considerable discrepancy in how some people understood the rules. Specifically, one person gave a clue saying "None of your cards are red".
We turned to the rule book, but even then couldn't find a definitive answer. The rules specify that if you give a clue, you have to give a color or a number, and you must point to every card that matches this information in the player's hand. For example, you can't say "red" and point to only one of their red cards.
There doesn't seem to be anything allowing or disallowing giving a clue that matches none of the cards.
Some of our players were absolutely fine with that (according to them, if nothing says you can't, it means that you can)
Some of our players were against it (you are not cluing cards, therefore the clue is invalid), and some even thought it was insanely powerful for advanced plays because your available alphabet for communication becomes publicly known and much larger.
Are there any other editions than mine where the rulebook actually specifies if this is allowed or not? If not, are there any other sources that could answer this question? (ex: interview with creators, official community consensus, etc)