$re = '/OEM[]]]><[\/]Name><Value>(.*)(?=<[\/]Value><[\/]NameValueList)/m';
$str = '<NameValueList><Name><![CD[OEM]]></Name><Value><![CD[TESTDATA]]></Value><Value><![CD[TESTDATA]]></Value><Value><![CD[TESTDATA]]></Value><Value><![CD[TESTDATA]]></Value></NameValueList><NameValueList><Name><![CD[AAA]]></Name><Value><![CD[11111]]></Value></NameValueList><NameValueList><Name><![CD[EAN]]></Name><Value><![CD[XXX]]></Value></NameValueList><NameValueList><Name><![CD[bla]]></Name><Value><![CD[BLE]]></Value></NameValueList><NameValueList><Name><![CD[MOD]]></Name><Value><![CD[BLU]]></Value></NameValueList><NameValueList><Name><![CD[ORG]]></Name><Value><![CD[Made in Germany!]]></Value></NameValueList></ItemSpecifics>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php