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.
