Both the behaviour of the dominant cat as well as that of the submissive cat are discussed here. There are two sides to this form of feline behaviour.
Dominant cats will block the movement of subordinate cats. Sometimes they will replace or supersede the movements of the submissive cat. The dominant cat might bat at the subordinate with his paw or feint (a pretend smack) such an action. He may chase the other cat and sometimes mount the subordinate.
If a dominant cat walks past a subordinate he may briefly stare at the other cat and at the same time rotate his stiffly erect ears to the side. The subordinate cat may avert his/her gaze and the dominant will walk on.
As for body posture, the dominant cat may signal that state of affairs by ‘holding the ears up and rotated to one side, arching the base of the tail and staring at the subordinate’.
In an interaction with the submissive cat, the dominant one may show a complete dominant display. The forelimbs are extended and stiff. The base of the tail is elevated while the rest of tail is hanging down. The ears are ‘stiffly erect and rotated laterally..’. He stares at the other cat.
In more extreme displays of dominance, he may slowly wag his head from side to side. Typically in cat groups displays of dominance are subtle and only one of the above actions is present.
A dominance or subordinance hierarchy can be useful is creating harmony or stability in cat groups where there is competition for food and possibly litter trays.
Linear hierarchies can be present in small groups of cats. This means a straight line of dominant and submissive cats where the submissive cat to the top cat is dominant to the cat below him.
Quotes and reference: The Welfare of Cats at page 12.