Quality-controlled subject gateways: definitions, typologies, empirical overview

"Quality-controlled subject gateways" are Internet services which apply a r ich set of quality measures to support systematic resource discovery. Consi derable manual effort is used to secure a selection of resources which meet quality criteria and to display a rich description of these resources with standards-based metadata. Regular checking and updating ensure good collec tion management. A main goal is to provide a high quality of subject access through indexing resources using controlled vocabularies and by offering a deep classification structure for advanced searching and browsing. This ar ticle provides an initial empirical overview of existing services of this k ind, their approaches and technologies, based on proposed working definitio ns and typologies of subject gateways.