This feature will allow you to request any missing itinerary details from the buyer. Simply go to the Itinerary tab and click the 'Request Itinerary' button.
It will give you the option to select any details needed (eg. Contacts, Flights, Hotels, etc).
Once you send out the itinerary/advancing request, the buyer will receive an email with a link to fill out a form. This email/link is transferable in case the buyer is not the corresponding person to complete these details. Once the buyer completes the form, it will automatically populate your itinerary tab on the booking.