ClutchCargo

But boy, oh boy. Say this to a believer and get ready to loose an afternoon.

I volunteer as tribute

It denotes the variation to the specific fin when it was ordered from the manufacturer. For example, if an airlines wants to use its 777-300 type for a domestic market and needs a smaller center fuel tank to make room for baggage and cargo, that configuration would have a different model subtype number, such as 777-3xx.