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When assigning tasks to user, show all users, not just users in project team: If you select this option, all users in the company are visible when you allocate task to resources. However, if you clear this option, then while creating a new project, only the users in your team are shown. Therefore, when you assign resources to tasks, only the users from your team are visible.
Users can create working/non-working events via their calendar. Project schedules will be auto-adjusted immediately.Allow users to add events impacting work hours like holidays. Projects are rescheduled immediately: If you select this option, then while adding events, users can specify if this event impacts scheduling and their tasks get impacted.