The mask consists of a string that determines what class of character is acceptable at each input position.

Valid mask characters are:

0 Digit (0-9)

9 Digit or space

# Digit, space, or sign (+/-)

L Letter

? Letter or space

A Letter or digit

a Letter, digit, or space

& Any character

. Localized decimal symbol

, Localized thousand separator

: Localized time separator

/ Localized date separator

Other characters are treated as literals. They are displayed in the control but cannot be edited.

For example, the mask "000-0000" causes the control to accept only digits at every position except the third, which always contains a dash.