One of the most commonly-used symbols of the BDSM community is a derivation of a triskelion shape within a circle. Various forms of triskele have had many uses and many meanings in many cultures; its BDSM usage derives from the Ring of O in the classic book Story of O. The BDSM Emblem Project claims copyright over one particular specified form of the triskelion symbol; other variants of the triskelion are free from such copyright claims.