Table 4. Service items that can be measured in air travel.

Main Category	Air Fares						In Air				Before Air		After Air
Middle Category	High season air fares			Non-high season air fares			In-flight customer service				Reservation Service		Basic Reliability
Small Category	H1	H2	H3	NH1	NH2	NH3	IA1	IA2	IA3	IA4	BA1	BA2	AA1	AA2