Guiding Input with a Masked Text Box
MaskedEdit is an ASP.NET AJAX extender that attaches to a TextBox control to restrict the kind of text that can be entered. MaskedEdit applies a "mask" to the input that permits only certain types of characters/text to be entered. The supported data formats are: Number, Date, Time, and DateTime. MaskedEdit uses the culture settings specified in the CultureName property. If none is specified the culture setting will be the same as the page: English (United States).