xml_parse_into_struct does not seem to encode the name of tags in UTF-8 ignoring the XML_OPTION_TARGET_ENCODING you specified with xml_parser_set_option.

You reproduce the problem (using ISO-8859-1) with the
following script: 

<?
  $xmldata = "<?xml version='1.0' encoding='ISO-8859-1'?><???>???</???>";

  $parser = xml_parser_create('ISO-8859-1');

  // i want ISO-8859-1 !!
  xml_parser_set_option($parser, XML_OPTION_TARGET_ENCODING,"ISO-8859-1");

  xml_parse_into_struct($parser, $xmldata, $struct, $index);

  // need do decode tag names manually like this :-(
  //  foreach (array_keys($struct) as $index)
  //    $struct[$index]['tag']= utf8_decode(&$struct[$index]['tag']);

  // the name '???' is not encoded correctly
  echo "<h1>Struct</h1><pre>"; print_r($struct); echo "</pre>";
?>