To recap what the XSLT is doing, it is reading the sbook.xml file, and on the basis of that, outputting some HTML. It does this by

• Executing some XSLT instructions and
• Copying verbatim the HTML tags in the XSLT template

So now let's look at the << head >> element. Well hey... this is mostly just HTML! Want to change the stylesheet the screenbook will point to? Just edit the link here.