Description:
------------
The DOMDocument::load() function ONLY loads UTF-8 encoded files.
Ex: 'article.php' contains :
$xmlDoc = new DOMDocument();
$page = 'article.xsl';
$xmlDoc->load($page);
$xmlDoc->load('cours.xml');

Let's consider 'article.xsl' contains '... Précédent ...' (not pure ASCII chars)
If the content of 'article.xsl' is iso-8859-1 encoded, the subsequent error
appears (same if 'cours.xml' is iso-8859-1 encoded):

"DOMDocument::load() [domdocument.load]: Input is not proper UTF-8, indicate encoding ! Bytes: 0xE9 0x62 0x75 0x74 in file:///C:/wamp/www/xsl2/article.xsl, line: 71 in C:\wamp\www\xsl2\article.php on line 13"

So, it's imperative to UTF-8 encode 'cours.xml' and 'article.xsl'.

Of course $page = utf8_encode($page); ... is of no use,
because the 'utf8_encode' only operates on the string 'article.xsl', and not on the file content !.

CONCLUSION : It's not really a BUG in the ->load() function.
But it would be really important to have a supplementary optional parameter,
indicating the encoding of the incoming file:

-----Desired improvment ----------->
Add an optional parameter describing the $file actual encoding:  

$xmlDoc->load($page, 'iso-8859-1');
DOMDocument::load( string $file [, string $encoding])

The $encoding optional parameter thus would be useful to describe the actual $file encoding (if not UTF-8).
----------- END ---------------------- 









Test script:
---------------
[test.php]
 <?php
 $xmlDoc = new DOMDocument();
 $xmlDoc->load("cours.xml");
 ?>

[cours.xml]  (no matter the line encoding... 
The problem is caused by the 'é' from 'éclair'...)

<?xml version="1.0" encoding="UTF-8"?>
<root>
  <chapitre titre="Titre du chapitre 1">
    <partie titre="Titre de la partie 1">
      Texte éclair 
    </partie>
  </chapitre>
 </root>




(displays):

Warning: DOMDocument::load() [domdocument.load]: Input is not proper UTF-8, indicate encoding ! Bytes: 0xE9 0x63 0x6C 0x61 in file:///C:/wamp/www/xsl2/cours.xml, line: 5 in C:\wamp\www\xsl2\test.php on line 3