XSLT and XPATH: A Guide to XML Transformations

2.4. XML Components of XSLT Stylesheets

Explanations of comments and processing-instructions in general may be unnecessary for those of you familiar with their use in XML document instances. However, these components can also be accessed by XSLT stylesheets, or even be part of XSLT stylesheets, so their application in XSLT is important to understand. There are two concepts in particular that are worth reviewing, the XML declaration and the document type declaration.

2.4.1. The XML Declaration

One of the key components of any XML document instance is the XML declaration, which is a processing-instruction, or PI, that is always the first item in the document—it even comes before the document element. The XML declaration identifies the contents ...