CharacterSet is a dispaly character that accepts any character that's part of an arbitrarily defined set. You can specify a character set in the mask using {char:n:set} mask token where n is number of display characters to create and set specifies the set of characters that are acceptable. Here is an example that creates two display characters that accept a, b, c, d, e, f and 0 to 9 digit characters:
"{char:2:abcdef0-9}"
The set can include list of arbitrary characters as well as ranges. In above example, 'abcdef' is arbitrary character list where as 0-9 is a range. Ranges are inclusize.

Note: The character sets are case sensitive. If you want to accept both the upper and lower case of a character, include both the upper and lower case character in the list.

Note: Typically there is no need for you to directly create or use display characters. XamMaskedInput will automatically create and manage these objects based on the supplied mask.

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