Enhanced Vehicle Book performs several steps when booking a vehicle depending on the chosen path:

Booking Key Path (triggered by populating /EnhancedVehBookRQ/VehBook):

1. Retrieves the state of a session to validate whether it already contains any vehicle segments.
2. Decodes and retrieves shopped rate details based on the data provided by the Booking Key.
3. Prepares and execute a vehicle sell request.
4. If the booking is successful, validates the newly added segment statuses as returned by the vehicle vendor.
5. If the segment status code is UC, considers the transaction as an error and stops processing.
6. Returns the details of the newly added vehicle segment.

Longsell Path (triggered by populating /EnhancedVehBookRQ/VehBookLongSell):

1. Retrieves the state of a session to validate whether it already contains any vehicle segments.
2. Prepares and executes a vehicle sell request based on the XML payload.
3. If the booking is successful, validates the newly added segment statuses as returned by the vehicle vendor.
4. If the segment status code is UC, considers the transaction as an error and stops processing.
5. Returns the details of the newly added vehicle segment.