I agree they went out of their way to 'try' and make it clear, but I can't see how you can't have interpretation brought into it. Even for what one ref might think is a clear cut black card another might disagree. And then you have the whole 'common sense' approach that's preached by commentators that seems it should be applied to all rules.
Someone mentioned a TMO above, anything that' brings about the right decision should be considered. When you have a ref having to make a decision on a millisecond viewing and he then gets criticized after people have had 10 different angles on it, slowed down, frozen, rewound and debated the issue for 5 mins. Even after all of that, people still disagree and yet the refs still get pilloried for it!