Flintflinger

So using this, how could you tell if the number was inflated? I guess I dont understand. Sometimes I need to be hit in the head with a brick before it sinks in.

The bow I am looking at is from Cabelas. it is the Cabelas outfitter series PL1.5. It says IBO:310 FPS.

Now according to another thread of bow and bow hunting terminology IBO means International Bowhunters Organization. Are they the governing body that determines bow speed?