What makes a carrier, a carrier?

Hello All,

	Ages ago, there was some talk about the dividing line between
a carrier and a non-carrier.  I believe it compared the MASS of the 
fighter bays vs. something else.  I need to know so I can update my
gaming groups "House Rules".  Anyone remember what the "accepted"
carrier classification is?

Pete

"If I had a sig, I'm sure it would be witty."