property CalendarCombo.MaskOnEmpty as String
Specifies the masking string for each entity when the date is empty.

TypeDescription
String A String expression that indicates the masking string when the SelDate property is empty. For instance, if the control's label displays the date such as 6/5/2013, if the Value property is set on 0, the control's label displays actually _/_/_ caption.
By default, the MaskOnEmpty property is "_".  Use the MaskOnEmpty property to specify the caption of the control's label when the SelDate/Value property is empty ( 0/null date ).  If the MaskOnEmpty property is "" ( empty string ), the control's label displays nothing when the SelDate/Value property is 0.

The following VB sample displays nothing when user presses the Delete key:

Private Sub CalendarCombo1_KeyDown(KeyCode As Integer, Shift As Integer)
    If (KeyCode = vbKeyDelete) Then
        CalendarCombo1.Value = 0
    End If
End Sub

Private Sub Form_Load()
    With CalendarCombo1
        .AllowCheckBox = exHidden
        .MaskOnEmpty = ""
    End With
End Sub

The following VB/NET sample displays nothing when user presses the Delete key:

Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        With Excalendarcombo1
            .AllowCheckBox = exontrol.EXCALENDARLib.VisibleEnum.exHidden
            .MaskOnEmpty = ""
        End With
    End Sub

    Private Sub Excalendarcombo1_KeyDown(ByVal sender As Object, ByRef KeyCode As Short, ByVal Shift As Short) Handles Excalendarcombo1.KeyDown
        With Excalendarcombo1
            If (KeyCode = Keys.Delete) Then
                .Value = Nothing
            End If
        End With
    End Sub
End Class