Output of xmlreader_file.php:
books xmlns:dc => http://purl.org/dc/elements/1.1/; This is a comment
book id => 1;isbn => 3-8266-0612-4;
title 'Apache Web-Server'
year '2000'
subject NS: http://purl.org/dc/elements/1.1/ 'Webserver'
book id => 2;isbn => 3-8266-0550-0;
title 'Linux für Internet und Intranet'
year '2000'
subject NS: http://purl.org/dc/elements/1.1/ 'Operating Systems'
PI: php -> print "this is a processing instruction"; 