Interoperability in Virtual Observatories is based on standards for interchange formats, and protocols. Using real science cases, we present example VO tools based on the AVO prototypes and the CDS services, which implement the new and emerging VO standards. We discuss how these standards, such as VOTable, UCDs and data models
enable interoperability between software components, and provide efficient and flexible means for data access. We show how UCDs are used in catalogue filtering and selection of relevant columns. We also demonstrate a simple yet powerful method for accessing data from image archives, customized data sets and local data within a single environment.
AVO Work Area 2 consists of deployment and demonstration of an interoperability prototype. Access to archives of all the partners (ESO, ESA, AstroGrid, Terapix, Jodrell Bank) is implemented via the CDS data federation and integration tools: VizieR and Aladin. The prototype is available for science usage and more functionalities, based in particular on the usage of Uniform Content Descriptors (UCDs) for data mining, will be developed. Case by case discussion with data providers will help to establish a set of practical recommendations for interoperability. Science requirements and new technologies studied by the other AVO work Areas will also be tested. Discussions on standards are ongoing among all VO projects.