What Makes M/s Ethical?

What are some of the issues that need to be addressed so that a Master/slave relationship can serve the needs of both parties without exploiting or harming anyone? Is consent alone enough, or do other considerations also play a role in making an M/s relationship ethical? Are there different kinds or levels of consent? Is "ethical" the same as "moral," or does it mean something else? Are "limits" merely preferences, or are  there ethical limits that come into play even during negotiation for an M/s partnership? What constitutes "abuse" in a M/s  relationship? What are a Master's responsibilities to a slave? Of a slave to a Master? Sir Brian F's slave david stein, who ha  been writing and thinking about the ethics of M/s and BDSM for  many years, will share his ideas and discoveries, then lead a  discussion where everyone attending the workshop can contribute.