Prolog

The prolog refers to the information that appears before the start tag of the document or root element. It includes information that applies to the document as a whole, such as character encoding, document structure, and style sheets.

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="show_book.xsl"?>
<!DOCTYPE catalog SYSTEM "catalog.dtd">
<!--catalog last updated 2000-11-01-->

Processing instructions can also appear in the prolog, for example, the xml-stylesheet processing instruction, <?xml-stylesheet type="text/xsl" href="show_book.xsl"?>. For more information, see Processing Instructions.

Comments can appear in the prolog, for example, <! -- catalog last updated 2000-11-01--!>. For more information, see Comments.