Using Input Masks to Set Up Field Formats
Some forms contain fields in which you can specify an input mask, or template, that
determines the format used to display or enter values in the field.
Note: In specifying an input mask,
consider whether a null value is allowed in a field. To prevent the
system from attempting to save an unspecified value in a decimal field
bound to a table column that does not allow null values, use the mask
character 9. An input mask that contains 9 defaults to 0 if no value
is specified in the field, and the value 0 can be saved.