In BDSM, a contract is an agreement, usually written, between the dominant and submissive in a 24/7 or Total Power Exchange (TPE) relationship. It is the formal act of consent to the power exchange. Some are very formal and will detail exactly what is expected and can run for multiple pages. Others are as brief as a single paragraph. Either way, one is derived by negotiation on the part of both parties. BDSM couples consider the contract to hold equal moral authority to a marriage commitment. As such, constructing a proper contract is very much like writing a pre-nuptial agreement.