Have you heard? Apple’s new 11-inch MacBook Air is preapproved for airport security. That’s right: Carry one of those bad boys through a TSA checkpoint, and you don’t even have to take it out of your bag.

So what sets the MacBook Air apart from other noncheckpoint-friendly notebooks? It isn’t that the TSA is full of certified Apple fanboys. The truth is that it all comes down to size.

Though Apple doesn’t consider the 11-inch MacBook Air a netbook, the computer’s small profile puts it in the same category as netbook-designated devices — at least, in the eyes of Homeland Security. We tech folks may look at things like specs and price tags when categorizing a computer, but the TSA is more concerned with how much space the system takes up.

In the case of Apple’s 11-inch MacBook Air, the fact that the computer is “smaller than a standard-size laptop” is the sole reason the TSA green-lighted it to stay inside your carry-on at airport security. As first reported by CNN, the MacBook Air is seen by the government as the same type of gadget as an iPad, an e-reader, or — yep, you guessed it — a netbook.

“Small and portable electronic items … should not need to be removed from their carrying cases,” a TSA spokesperson tells me.

The big question, then, is where we draw the “small item” line.

Would Apple’s new 13-inch MacBook Air, for example, be OK to go through an airport checkpoint while inside a bag? What about ultraportable but high-performing notebooks on the PC side of the equation — will they get the same security love as Apple’s 11-inch Air? What is the “standard size” of a laptop nowadays, anyway?

It turns out there’s no easy answer.

In the case of the 13-inch MacBook Air, the TSA has yet to reach a final verdict, according to CNN. A TSA representative did tell me that anything “similar in size to an iPad” should generally be safe to stay in your bag. She was unable, however, to provide any firm guidelines as to what separates a “small and portable electronic item” from a full-fledged laptop. Long story short, there is no magic number.

Rather than obsess over the size of your gizmo, then, the smartest option may be to go with a checkpoint-friendly laptop bag. Throw your notebook, netbook, or whatever you want to call it in one of those suckers and — unless you’re flagged for extra screening — you should be able to breeze right through airport security.

And yes, by “breeze right through,” I mean “waddle through shoeless while hanging onto your unbelted pants and the little dignity you have remaining.”

But hey, at least you won’t have to unpack your laptop.