Originally Posted by Dr. HFH

Some airlines have (or used to have) bonus programs based on the dollar value of tickets plated (issued) on that airline's number. Don't know if that still exists.

If you're too young to know what "plating" is, back when tickets issued by travel agents were paper with red carbon, the agencies had metal plates which they would imprint on the tickets to indicate which was the issuing carrier. Here's an example: