  Considerable concerns exist over privacy on social networks, and huge debates
persist about how to extend the artifacts users need to effectively protect
their rights to privacy. While many interesting ideas have been proposed, no
single approach appears to be comprehensive enough to be the front runner. In
this paper, we propose a comprehensive and novel reference conceptual model for
privacy in constantly evolving social networks and establish its novelty by
briefly contrasting it with contemporary research. We also present the contours
of a possible query language that we can develop with desirable features in
light of the reference model, and refer to a new query language, {\em PiQL},
developed on the basis of this model that aims to support user driven privacy
policy authoring and enforcement. The strength of our model is that such
extensions are now possible by developing appropriate linguistic constructs as
part of query languages such as SQL, as demonstrated in PiQL.
