As the Capitol Hill debate on “cap and trade” global warming legislation continues, always keep in mind that not all caps are the same. Loopholes and poor structure can make a cap ineffective.

Here, we’ve talked a little more about possible loopholes than the overall structure of a cap-and-trade program. But over at Gristmill, Tom Athanasiou sums up the different structures and where the pitfalls and potential benefits are.

A must-read for anyone trying to follow the overall debate.