On September 19, 1985, a US Senate hearing was instigated by the Parents Music Resource Center (PMRC)--founded by Tipper Gore, wife of Senator and later Vice President Al Gore; and Susan Baker, wife of Treasury Secretary James Baker--who wanted to introduce a parental warning system that would label all music albums containing alleged offensive material. The system was to include letters identifying the type of objectionable content to be found in each album (O for occult themes, S for sex, D for drugs, V for violence, etc.). Dee Snider, lead singer and primary songwriter for the rock band Twisted Sister, John Denver, and Frank Zappa all testified against censorship and the proposed warning system. Such a system was never implemented, but the result of the hearing brought about what was known as the "Parental Advisory: Explicit Content" label.