Definition: wikipedia. A specification for finding and talking about data. Actual data retrieval occurs through other means, such as WCS, WFS, or OPeNDAP. Specifies the request response protocol for requesting metadata records from a server and how the server should respond. Details of searching and filtering returned metadata rely on the schema or format of data being served by the CSW. As a result of this and other details, various implementations may not be interoperable.