How do you use MaskedEditExtender for both letters and numbers?

Question

I've got the following line of code:

<asp:MaskedEditExtender ID="meeLegID" runat="server" MaskType="None" Mask="LLLLL" 
TargetControlID="txtLegID" PromptCharacter="_"  InputDirection="LeftToRight" 
AutoComplete="False" />

The problem is, it only accepts letters. If I set the Mask="99999", it only accepts numbers. So what do you set Mask to in order for it to accept both letters and numbers?

Answer 1

Found the answer.

Mask = "?????"