I have a fare code HAX in an upcoming trip and am wondering if anyone here can enlighten me - never seen anything like this before.

The trip runs

LAX-ORD (L leg)
ORD-CMH (HAX leg)
CMH-LAX (W leg)

I'm wondering, then, if the HAX is some kind of stopover designation? I can see how the fare could be constructed as an ORD stopover with CMH termination... (?)