Metacat uses XML for data exchange between the client application and the server.

XSLT is used for transformations for visual presentation (e.g. XML->HTML). It can also be used to tranlate between different types of heterogeneous XML documents which are symantically similar.

Metacat can be set on the fly to either transform or not transform a resultset from XML. This is achieved by setting the 'qformat' servlet parameter to the name of a style-set or to 'html' or 'xml'. When qformat is set to html, Metacat will transform the resultset based on the default style-set configured in the Metacat Properties file. This style-set defines the rules for how to translate the XML tags into HTML tags.