The Dal Daleks were originally ruled by a Council in their metal city. These were the descendants of the Dal leaders who restored the city and ensured that their race would survive by translating and reverse engineering the Kaled technology. There was no way for an outsider to distinguish between a regular Dalek and one higher up in their hierarchy, which consisted of several implied levels – from the council members through sector leaders to the majority of drones.
Once the Daleks of the First Generation discovered the Dal city, however, they were assigned a mini-hierarchy of their own. The ruling caste was encased in either Black, or Black and Silver Travel Machines. These Daleks then became the leaders of the Dalek spearhead across the galaxy.
Although called Dalek Supreme (Black) and Saucer Commanders (Black / Silver) by their underlings, their place in the overall Dalek hierarchy was around that of a Red Dalek Section Leader of the first generation. The Dals were not genetically identical to the Generation One Daleks and thus were deemed an impure and expendable resource. Their leaders could not be given equal standing within the empire.
