>>>I'd say it means that tdNullable can be null http://msdn.microsoft.com/en-us/library/b3h38hb0.aspx#Y1537
>>>
>>>You may want to test tdNullable.HasValue to verify whether it contains a value
>>
>>Is there a way to avoid this question mark if there is a possiblity to receive a null value for the parameter?
>
>
>try
>

>Private Function GetNonNullable(ByVal tdNullable As Nullable(Of Date)) As Date
>

Hence the ? is easier!