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The XSLT Working Group has published XSL Transformations (XSLT) Version 3.0 as a Recommendation. XSLT 3.0 enables transformations to be performed in streaming mode, where neither the source document nor the result document is ever held in memory in its entirety.
Another important enhancement is provided by XSL packages, to improve the modularity of large stylesheets, allowing stylesheets to be developed from independently-developed components with a high level of software engineering robustness.
XSLT 3.0 is designed to be used in conjunction with XPath 3.0, which offers higher-order functions. It also specifies the map functionality exactly as it is in the XPath 3.1 Recommendation, and implementors may also offer support for other XPath 3.1 additions compared to XPath 3.0, like arrays.