My understanding of leg is different
As per example given at http://gennick.com/?q=flight
Plane QF1 that flies from A to B, and then on to Z.
Plane QF2 that flies from A to Z directly, and then stops.
Plane QF3 that flies from D to E to F, and finally to Z.
Each hop from one point to another is called a "leg". For example, flight QF1 consists of two legs: from A to B, and from B to Z. Flight QF2 consists of a single leg, whereas Flight QF3 consists of three legs
Here I am really confused as there are different meaning used by every airline
As per defination of Southwest airline it says "One take off and landing during air travel constitutes a segment"
This means that segment is no difference then leg.
If this is the case then how to handle the change flight as per use case. As per use case a user can select segment to change and that means if your flight from departure to arrival consist of multiple leg then you can select one of the leg and change the its flight. This I never see in any airline. The airline only allow to change the entire route i.e from departure to arrival
Any thoughts on this