The software requirement specification for the Calendar management system is described as follow.

This calendar management software allows the user to schedule personal activities such as meetings and tasks to be performed. An activity can take place on a future date during a certain period of time. An activity can take place for several consecutive days. Each activity has a brief description. An activity can be a recursive activity, which takes place repeatedly every hour, every day, every week, or every month. A user can schedule an activity using a month-by-month calendar to select the date or dates, and then zooms in to select the begin time and end time on a date. The calendar system shall notify the user by email, text message, or phone call the day before and on the activity day. The user can review past activities and modify the schedule including updating and deleting activities.

Identify the type of the system.

		Transformational subsystem
		Database subsystem
		Interactive subsystem
		Event-driven subsystem