A use exemple of this method :Usefull for generating an XML linked with a XSLT !<?php// "Create" the document.$xml = new DOMDocument( "1.0", "ISO-8859-15" );//to have indented output, not just a line$xml->preserveWhiteSpace = false;$xml->formatOutput = true;// ------------- Interresting part here ------------//creating an xslt adding processing line$xslt = $xml->createProcessingInstruction('xml-stylesheet', 'type="text/xsl" href="base.xsl"');//adding it to the xml$xml->appendChild($xslt);// ----------- / Interresting part here -------------//adding some elements$root = $xml->createElement("list");$node = $xml->createElement("contact", "John Doe");$root-> appendChild($node);$xml-> appendChild($root);//creating the file$xml-> save("output.xml");?>output.xml :<?xml version="1.0" encoding="ISO-8859-15"?><?xml-stylesheet type="text/xsl" href="base.xsl"?> //the line has been created successfully<list> <contact>John Doe</contact></list>