NatalieD: The title is "Nine levels of submission" - okay, but I don't even see it stated anywhere in the text that these nine groups form a definite progression, with the meaning that one step/group is inherently better than the ones that were mentioned before. You can read that into it, to some Doms (especially) it will be a reflex to read that in, but in my view she is rather trying to ferret out different kinds of submissive longing and commitment - there's no implication that they're clear-cut or that one is better than all the rest. In fact, the way she describes the 9th "class" (what you might loosely call "total slavery") she seems to have strong reservations about that one - she says it might only exist in fantasy and sees it as probably a by-product of brainwashing or misleading religious ideas. Do keep in mind that being a (radical?) Lesbian, she is very probably arguing with "standard M/f BDSM" and its ideas here and there in her piece.
I see her trying to use some parameters (scales) to bring out those different kinds of subbiehood:
consensual at all moments - willing to give up consensuality for some time and surrender yourself totally
short-term - long-term - life-time
focused on own enjoyment/thrill - on Dom/me's enjoyment
sexual services - other services too
and so on. My own bond with Liz doesn't really fit any one category here, partly because there's no mention of switches (which she is) or trans people (me) and also because this outline predates the internet. but that's just one reason why I think it's a useful starting-ground for discussion.