When one ventures into the risky practices of rough sex, dominance and submission, Master/slave, “non-consensual consent” and other non-mainstream sexual activities involving such acts as spanking, whipping, caning, restraint, edge play, to name a few, which will likely result in marks, bruising, cuts and other physical manifestations, it seems like a good idea, particularly with strangers, to discuss the boundaries of consent before the act or at least obtain confirmation of consent after the fact. As consent is exclusively in the realm of the mind and can sometimes be transient or the perception of it change over time it is a prudent practice for one to obtain proof of what the person was thinking or feeling about the activity at the time. Written statements in the form of emails, text messages and letters are valuable for this purpose.