W3C has published XSL Transformations (XSLT) Version 2.0 (Second Edition) as a W3C Recommendation. This specification defines the syntax and semantics of XSLT 2.0, a language for transforming XML documents into other XML documents. This Second Edition incorporates errata and
clarifications, without new features.

W3C has published a 3.0 version of the XSLT language as a W3C
Recommendation, on 8 June 2017, which includes powerful additions,
so as to enable 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 aim of 3.0 was to improve the modularity of
large stylesheets, allowing stylesheets to be developed from
independently-developed components with a high level of software
engineering robustness (packages).

Original source: https://www.w3.org/blog/news/archives/8977