X-Query is based on the W3C's XPath 1.0 specification. XPath provides a data model and expression syntax for addressing parts of XML documents. X-Query adheres to the principles of XPath for efficient usage in the database context, whilst at the same time following the Tamino design principle of adhering to public standards.

XPath is not a query language in itself, but rather a language for addressing parts of an XML document. Since Tamino generally stores data as XML documents, XPath provides a standard mechanism for addressing the contents of XML objects returned from the database. With X-Query you can retrieve XML objects using:

• query expressions based on the XPath specification.

  These expressions are described in the section Expressions. In order to use these expressions effectively, you should be familiar with the current XPath specification.

• Tamino text retrieval and sorting expressions.

  Tamino also provides text retrieval and sorting expressions. You can retrieve text by using the "contains" operator ~=. You can sort XML objects by using the expressions sortby and sortall. These expressions are described in the X-Query Reference Guide.

• Tamino server extensions.

  You can extend X-Query by using Tamino server extensions. The documentation of X-Tension: Tamino Server Extensions describes how you can implement your own X-Query extension functions.