This enumeration is used to set the Calendar.DayNameFormat property, which configures how days are displayed at the top of the calendar grid. Days can be displayed in Full (e.g., "Tuesday"), in a Short version ("Tues"), or by using the FirstLetter or FirstTwoLetters ("T" or "Tu").
public enum DayNameFormat { Full = 0, Short = 1, FirstLetter = 2, FirstTwoLetters = 3 }