Important issues concerning the catalog component of the WP include: 1) extending the classes of content-based queries supportable by ADL; 2) extending the metadata in the catalog component and the associated search procedures to support the extended classes of queries; 3) user access to the catalog system; 4) support for a distributed catalog.
An important class of queries in a library of spatially-indexed items involves requests for items of a given class in terms of the footprint of the item. In the RP, such queries were answered by intersecting a query footprint (entered into a map browser) with footprints of collection items (stored in metadata records). A significant extension to this class of queries supported in WP involves the search for items in which specific features, with or without their own spatial footprint, are represented. We also support the inverse query in which the user wishes to know which features are represented in specific items.