Super simple, and probably the easiest way to explain it.
If this doesn't straighten it out, then I'll throw up my hands.
What I think of when I think of small plane 135 cargo, is a single customer is usually how it works. I can't think of any integrators that run 135. Maybe IBC.
You have a parts run, say from a Ford plant in Kokomo Indiana up to Yipsilanti. There is one customer that pays for a plane. They put their transmissions or what ever on that one plane, it goes up to YIP, and the charter is done. No common carrier.
DHL needs a metro to do a feeder run out of CVG. DHL's name is on the airwaybills attached to the packages. DHL is the common carrier.
Grand Aire holds out services in a Falcon 20. Dana contracts with them to fly axels from their plant to Ford. Grand Aire is the common carrier and the shipment from one customer to the other is done. But it's one customer on the plane, so everyone knows where the part comes from.
Neither is the case, but it can be on large planes, for AmeriJet.
AmeriJet gets the cargo from individuals. They slap an AmeriJet airwaybill on it, because there are many customers that go to many destinations, much like the DHL scenario above. If individual packages are loaded, they each have an airway bill attached. More commonly, becuase the airplanes are big and have really big doors in them and cargo handling systems, they build up pallets or fill up ULDs with many customer's packages. While there are many, many labels on the inside of each, they also put a tag on the outside of the pallet with the operator and the weight.
Why do they tag it? So they can prove it belongs to them.
Trust me on this. After the strike that I wasn't at Polar for in 2005, it's a hot topic. I've learned alot from guys that were looking all for this stuff. Much of the information just came from guys doing this for 20+ years too.