A service that is based on harvested metadata, and adds value for its users by means which may include normalization and enriching of the harvested metadata for example. Types of services which may be offered include search services, citation linking, overlay journals, and peer-review services, among others. Source: OAI for Beginners - the Open Archives Forum online tutorial at http://www.oaforum.org/tutorial
A value-added service (VAS) is a telecommunications industry term for non-core services or, in short, all services beyond standard voice calls. On a conceptual level, value-added services add value to the standard service offering, spurring the subscriber to use their phone more and allowing the operator to drive up their ARPU. For mobile phones, while technologies like SMS, MMS and GPRS are usually considered value-added services, a distinction may also be made between standard (peer-to-peer) content and premium-charged content.