If you want to assign Nothing to the optional parameter in VB.NET 10, it is just like to obvious now,
Sub Main()
'Passing value for the optional parament _age
MyFunc("Wriju", "wriju@contoso.com", 30)
'No value is supplied for the optional parament _age
MyFunc("Writam", "writam@contoso.com")
End Sub
Sub MyFunc(ByVal _name As String,
ByVal _email As String,
Optional ByVal _age As Integer? = Nothing)
Console.WriteLine("Name={0}, Email={1}, Age={2}",
_name, _email, _age.ToString())
Namoskar!!!