In the Internet, users interact with service providers; these interactions exchange information that might be considered private by the user. Existing schemes for expressing and enforcing user privacy on the Internet---notably notice and consent---are inadequate to address privacy needs of Internet users. This paper suggests a new, practical, and expressive policy tag scheme that would enable users to express both control-based and secrecy-based restrictions. We identify key design goals, explore various design choices that impact these goals, and outline a proposed implementation---called avenance tags---that realizes these goals.