Well keeping VB aside, it has its own charm when we say the link today is from so and so shed. So I would say let the locos be mentioned to their respective zone. Whatever zone the rake belongs too, if a proper loco as per the train type is given, whatever the zone it belongs too makes no difference. Some people consider the might of WAP4 as less and want thier most liked trains to be hauled by WAP7 always and in certain case from their preferred Loco shed always.