Google Search Appliance has a built-in XSLT (eXtensible Stylesheet Language Transformation) server,
and can generate custom HTML using your XSL stylesheet. Search requests that include the output
parameter set to xml_no_dtd and a valid proxystylesheet parameter value are automatically
processed by the XSLT server as requests for custom HTML output.

Using the XSL stylesheet specified by the proxystylesheet parameter, the XSLT server applies the
transformation rules found in the XSL stylesheet to the standard Google XML results. Although this
document assumes that the output generated by applying the XSL stylesheet is HTML, almost any
output format can be generated by using appropriate XSL stylesheet rules. For any front end, the
default XSL stylesheet can be customized or replaced by the search administrator.

To customize the XSL stylesheet used to generate custom HTML output, see “XML Output” on page 53
to determine the XML tags that may be transformed using a customized XSL stylesheet.

Additionally, you can leverage the proxycustom parameter to pass custom XML tags to the XSLT server.
Because including custom XML does not generate search results, this feature is useful for implementing
additional static search pages, such as an advanced search page.

Customizations to XSLT stylesheets may result in vulnerability to cross-site scripting (XSS) attacks.
Google recommends that you run XSS test after customizing an XSLT stylesheet.