The Appointment Module [[File:027.png]] has been designed to allow high volume contact management with appointment management without any dependence on any specific server diary technology.
Though there may be some ambiguity in the difference and application of Diary or Calendar, bxp chooses to use Diary as the descriptive word for recording appointments. For more discussion please see http://english.stackexchange.com/questions/113488/usage-of-diary-and-calendar