This tab shows you all the appointment you have yet to accept or decline.
Requests for upcoming appointments are displayed in the "Awaiting reply" section. The appointments are listed in chronological order, from the nearest to the furthest. You can click on the appointment to see details about it, and you have the "Accept appointment" and "Decline appointment" buttons. Additionally, you can also export all the appointment requests in this tab and download them in the ICS format by clicking on the appropriate button.
If you haven’t responded to a appointment request before the scheduled time for the appointments, the request will be shown in the "Past" section. You are not able to accept those invitations. However, you have the "More Options" button, which presents you with the View appointments and "Decline appointment" buttons. The "View appointment" button allows you to see the details, and the "Decline appointment" button moves the request into the "declined" tab.