How to skip invalid characters in XML file using PHP

Do you have control over the XML? If so, ensure the data is enclosed in <![CDATA[ .. ]]> blocks.

And you also need to clear the invalid characters:

/**
 * Removes invalid XML
 *
 * @access public
 * @param string $value
 * @return string
 */
function stripInvalidXml($value)
{
    $ret = "";
    $current;
    if (empty($value)) 
    {
        return $ret;
    }

    $length = strlen($value);
    for ($i=0; $i < $length; $i++)
    {
        $current = ord($value{$i});
        if (($current == 0x9) ||
            ($current == 0xA) ||
            ($current == 0xD) ||
            (($current >= 0x20) && ($current <= 0xD7FF)) ||
            (($current >= 0xE000) && ($current <= 0xFFFD)) ||
            (($current >= 0x10000) && ($current <= 0x10FFFF)))
        {
            $ret .= chr($current);
        }
        else
        {
            $ret .= " ";
        }
    }
    return $ret;
}

Yes you can use simplexml with xpath in this case:

$xml = simplexml_load_file('path/to/xml/file.xml');
$name = 'Tipul licentei';
$product_code = '70-14UF44-00';
$products = $xml->xpath("//Product/ProductCode[contains(text(), '$product_code')]/following-sibling::AttrList/element[@Name='$name']");
if(count($products) > 0) { // if found

    $value = (string) $products[0]->attributes()->Value;
    echo $value; // Full Package

}

Sample Output

Also possible with DOMDocument:

$dom = new DOMDocument();
$dom->load('path/to/xml/file.xml');
$xpath = new DOMXpath($dom);

$name = 'Tipul licentei';
$product_code = '70-14UF44-00';
$value = $xpath->evaluate("string(//Product/ProductCode[contains(text(), '$product_code')]/following-sibling::AttrList/element[@Name='$name']/@Value)");
echo $value; // Full Package

Make sure you send the XML with an appropriate content-type and encoding, e.g.

<?php header("Content-Type: application/xml; charset=utf-8"); ?>

Also check that the XML prolog contains the proper encoding, e.g.

<?xml version="1.0" encoding="UTF-8"?>

The message about the style information refers to a missing processing instruction, e.g.

<?xml-stylesheet type="text/xsl" href="someting"?>

which would tell the browser how to style/format the output. It is not necessarily needed if you just want to display the raw XML.