ICS file also stores current and future project calendar information. ICS file, then import it as a holiday file in the Project Center Administration activity center. There are many applications (including Microsoft Outlook) that can import or export this file format, so users can use the applications to create calendars, export the. ICS ICS is a standard calendar file format that Project Center uses to import/export calendar information in the Project Timeline activity center. The project timeline enables all Project Center users to view, add, track, and manage project phases, milestones, holidays, and meetings Project meetings include phone calls, client meetings, contractor meetings, conversations, conference calls, tasks, site visits, and any other custom meetings that may have been added to the project.