Gertrude Stein may have been right about roses. But I'm here to tell you that a car seat is not a car seat is not a car seat.

There are car seats you can use in autos, buses, planes, wherever. And then there are others -- as Catherine Cosgrove recently discovered, to her extreme annoyance.

Catherine and her 4-month-old daughter Amy were all set to fly to Germany on World Airways to join up with hubby/dad, who is stationed at a U.S. Army post there. As any parent knows, a child is always more comfortable in a car seat (not to mention more safe) on a long trip. Catherine blithely assumed that if Amy's car seat was usable in the family car, World wouldn't object if she used it aboard the plane. Catherine had even taken the precuation of buying Amy her own seat on the plane.

But World did object. A gate agent at Baltimore-Washington International Airport said that Catherine would have to check the car seat as luggage, and that Amy would have to ride sitting up like everybody else.

Needless to say, Amy flopped and crawled and fidgeted all over the place in the ensuing nine hours, making it a much more exhausting and less pleasant trip than it might have been.

Explanation, please? Michael Henderson, the public relations director for World, had this to say:

"It must be a car seat that meets FAA standards. For car seats manufactured between Jan. 1, 1981, and Feb. 26, 1985, they must have the following label: 'This child restraint system conforms to all applicable federal motor vehicle safety standards,' or another label that says, 'This complies with FAA technical standard order C-100 issued May 28, 1982.'

"For seats manufactured after Feb. 26, 1985, it must have a label that says, 'This restraint system is certified for use in motor vehicles and aircraft.' " And even if the car seat does meet FAA standards, said Michael, the parents must purchase a separate seat on the aircraft for child and seat.

It's a mighty bureaucratic world you've arrived into, Amy. But at least your mom now has a new car seat on the shopping list before your next plane ride. Other Moms and Dads might want to check the labels Michael describes before heading for the airport.