MaskedTextBox for WPF and Silverlight supports the standard number formatting strings defined by Microsoft. The Mask string should consist of one or more of the masking elements as detailed in the following table:
| Element | Description |
| 0 | Digit, required. This element will accept any single digit between 0 and 9. |
| 9 | Digit or space, optional. |
| # | Digit or space, optional. If this position is blank in the mask, it will be rendered as a space in the Text property. Plus (+) and minus (-) signs are allowed. |
| L | Letter, required. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z] in regular expressions. |
| ? | Letter, optional. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z]? in regular expressions. |
| & | Character, required. |
| C | Character, optional. Any non-control character. |
| A | Alphanumeric, optional. |
| a | Alphanumeric, optional. |
| . | Decimal placeholder. The actual display character used will be the decimal symbol appropriate to the format provider. |
| , | Thousands placeholder. The actual display character used will be the thousands placeholder appropriate to the format provider. |
| : | Time separator. The actual display character used will be the time symbol appropriate to the format provider. |
| / | Date separator. The actual display character used will be the date symbol appropriate to the format provider. |
| $ | Currency symbol. The actual character displayed will be the currency symbol appropriate to the format provider. |
| < | Shift down. Converts all characters that follow to lowercase. |
| > | Shift up. Converts all characters that follow to uppercase. |
| | | Disable a previous shift up or shift down. |
| \ | Escape. Escapes a mask character, turning it into a literal. "\\" is the escape sequence for a backslash. |
| All other characters | Literals. All non-mask elements will appear as themselves within C1MaskedTextBox. Literals always occupy a static position in the mask at run time, and cannot be moved or deleted by the user. |
The decimal (.), thousandths (,), time (:), date (/), and currency ($) symbols default to displaying those symbols as defined by the application's culture.
Literals
In addition to the mask elements already defined, other characters can be included in the mask. These characters are literals. Literals are non-mask elements that will appear as themselves within C1MaskedTextBox. Literals always occupy a static position in the mask at run time, and cannot be moved or deleted by the user.
For example, if the Mask property has been set to "(999)-000-0000" to define a phone number, the mask characters include the "9" and "0" elements. The remaining characters, the dashes and parentheses, are literals. These characters will appear as they are in the C1MaskedTextBox control.
