The first stylesheet

XSLT stylesheets contain as the root element xsl:stylesheet. The specification allows xsl:transform as a synonym for xsl:stylesheet, but this possibility is seldomly used. Another possibility, usage of simplified syntax is also not common. I recommend to use xsl:stylesheet every times.

Every xsl:stylesheet must contain attribute version. The value of this attribute is "1.0" for the first version of XSLT and "2.0" for the second version. These tutorials are written with XSLT 2.0 processors in mind and so version value "2.0" is used, but many presented stylesheets are also correct in "1.0" version.

Inclusion of xmlns:xsl is also very important. This is not an attribute but a namespace declaration. There are other ways how to provide this information using possibilities offered by XML namespace specification, but this is the commonly used procedure and if you use it in your stylesheets you can program in XSLT even without understanding XML namespaces.

The value of xmlns:xsl is always "http://www.w3.org/1999/XSL/Transform" both for XSLT version "1.0" and "2.0". XSLT versions are distinguished by the value of version attribute, not by the namespace declaration.

The stylesheet does not output anything, more instructions are need to provide some useful output. But the stylesheet will be accepted and evaluated by any XSLT "2.0" processor as a valid program, which does nothing.