1. A programming interface embodied on one or more computer readable media, comprising: a first group of types related to core file system concepts; a second group of types related to entities that a human being can contact; a third group of types related to documents; a fourth group of types common to multiple kinds of media; a fifth group of types specific to audio media; a sixth group of types specific to video media; a seventh group of types specific to image media; an eighth group of types specific to electronic mail messages; and a ninth group of types related to identifying particular locations.