Dominance/Submission Ritual?

We have two older cats who get along fine, but who aren't super affectionate with each other- they don't cuddle with each other, and don't bathe each other, and only somewhat acknowledge the other's existence. However, when they run into each other around the house, the orange cat often walks up to the black cat, pokes her nose into the black cat's chest, and the black cat licks the top of her head about three times. Then they both walk away. It looks very much like a sort of dominance or submission ritual, but I can't tell which is the dominant one and which is the submissive one! The black one is always doing the licking, but the orange cat always has her head lowered. Anyone know this behavior?

I see that happen all the time in my household (10 cats here). I do understand the hierarchy in the household, and I can say that sometimes the dominant one will lick the subordinates, and sometimes its the other way around. The ones that lick the most often are just the types that like to groom the others and I would call them the house "ambassadors". The 2 that won't groom others are my 2 girls. This may be more of a male versus female thing than a dominance thing. Male and female cats don't always speak the same language to each other.