Flag for use with PendingIntent.GetActivity(Android.Content.Context, System.Int32, System.Int32, System.Int32), PendingIntent.GetBroadcast(Android.Content.Context, System.Int32, System.Int32, System.Int32), and PendingIntent.GetService(Android.Content.Context, System.Int32, System.Int32, System.Int32): this PendingIntent can only be used once. If set, after PendingIntent.Send is called on it, it will be automatically canceled for you and any future attempt to send through it will fail.