If you try to find a proper category for BDSM, maybe the most accurate position is to see BDSM as a culture. That way it seems to encompass the many factors that are included into BDSM.
Some people see BDSM as a separate and distinct part of their lives, it simply isn't about sex, others can't have one without the other. Sex doesn't always play a role if you look at the difference you will find between those into service and those into S&M. It’s not always sexually motivated, sometimes it's just the sheer enjoyment of `hurts so good' or the love of pleasing a partner,
What draws us together is the umbrella like cover that BDSM represents. We share a basic power exchange that happens either physically or spiritually and a perchance for not following established societal rules of intimate relationships. Of course there is a huge sexual component, shared by both, but the importance can be placed on any one, or more, parts of the whole BDSM puzzle.
Bondage it's sexual for some, for others is a stress reliever. Though most fetishes are considered sexual, for some, it is a comfort, or a release of stress, or statement to the world.
Much the way religion or language has been passed down from generation to generation, BDSM with all its different rituals, techniques, and philosophies are also being passed on.
In BDSM our common denominator appears to be some kind of power exchange. What we get from the power exchange is individual to every player. We all seem to require it at some level and once we've got overcome the fears of exploring the various aspects of BDSM we tend to migrate towards others who accept those traits in us. We teach and learn from each other with information being passed by word or mouth, books, movies and the Internet.
Aspects of the definition for culture shine through even when looking at individual relationships. The dominant, usually takes a training role with a submissive. Mentoring also takes on the role of training both dominants and submissive. There is a power exchange happening, even at that level. Techniques are taught and practiced, knowledge is shared, rituals taught and developed.
There is an standard of excellence that many in BDSM seek to obtain. We do it in different ways, but it seems to me we all try in our own way. The ultimate goal is still the same though the journey is not always the same. We want to be safe and lower the risk in our chosen expression of the BDSM lifestyle.
How you express your sexuality, can be one of the determining factors in what culture you live in. It's that expression of BDSM that groups us together regardless of our orientation. BDSM is the focus as opposed to our gender, our orientation or our side of the power exchange.