Carousel control for metadata navigation and assignment

A property tree user interface permits user assignment of values to metadata properties and user navigation of data, within a system that includes a data storage subsystem in which data items are organized and queried by way of properties. The property tree includes nodes that expose properties of data items. A user may interact with the property tree in order to effect an assignment of a property, in which case the value associated with the property in the data storage subsystem is modified. The property tree may also display nodes that represent folders within a hierarchical file system, nodes that represent properties with inherent hierarchy, and nodes that represent user-defined hierarchical properties, and the property tree may display such nodes in a carousel control.