T-100 is filed by operating carrier to the DOT without marketing carrier information, so we try and match up the marketing and operating carriers using schedules data, but if there is no match, then we leave the operating carrier. Think of this as airline reported and Diio calculated (in rare cases).
For T-100 data, carriers have to file every flight, whether it’s a scheduled flight, a charter flight, or even diversions. So sometimes the charter flights and diversions show up in T-100, and we cannot match them, so they show up for the operating carrier.
For most US markets, this is very easy. If the operator flies the route for a single marketer, then 100% of the operating flights are attributed to that operator/marketer pairing. However in rare circumstances, if the operator flies the SAME route for two different marketers, then we have to split the number of flights between the two marketers, based on percentage of flights in the schedule data.