The attributes that are single in definition but the instances of the attribute can behave differently according to the role they take. Example for this can be a database of airports around the world. The attribute of airport name is always based on the same database table but can be seen as a destination airport or source airport. Such roles are resolved by having aliases for the same table, one alias for destination and one for source airports. We can also enable the automatic attribute role recognition by configuring it properly.   _{Your Comment}