For trucking and per diem, what does multiple meals and incidentals markets mean?

“(2) Transportation industry defined. For purposes of this section 4.04, an employee or self-employed individual is in the transportation industry only if the employee’s or self-employed individual’s work (a) is of the type that directly involves moving people or goods by airplane, barge, bus, ship, train, or truck, and (b) involves regularly traveling away from home and stopping during a single trip at localities with differing federal M&IE rates. For purposes of the preceding sentence, a payor must determine that an employee or a group of employees is in the transportation industry by using a method that is consistently applied and in accordance with reasonable business practice.”