The notNull property specifies that the field does not accept NULL values.
This property requires that the field contains a value. If the field contains a default value, the notNull property is satisfied. To insist on data entry from the user, use notNull in the field definition, or make sure the corresponding column is defined as notNull in the database schema file.
The notNull keywords can also be used in the type definition of formonly fields.
The notNull property is effective only when the field name appears in the list of screen fields of an INPUT or INPUT ARRAY.
If a DEFAULT property is used for the field and the INPUT dialog does not use the WITHOUT DEFAULTS option, the runtime system assumes that the default value satisfies the notNull property.
Unlike the REQUIRED property which has no effect when the INPUT dialog uses the WITHOUT DEFAULTS option, the notNull property is always checked when validating a dialog.