Determines if a nullable column should be created when updating the database schema for the persistent class member described by the current XPMemberInfo object.
true, if a nullable column is created, otherwise, false.
To change the IsNullable value, apply the NullableAttribute to the current member declaration. To change the IsNullable value for the entire persistent class, apply the NullableBehaviorAttribute. You can also change this setting globally, using the static XpoDefault.NullableBehavior property.