Description:
------------
The function xml_get_current_byte_index() returns byte index according to utf8 encoded text - disregarding if input is in ISO-8859-1. If you would like to cach a chunk of data from a xml file you would need to convert input to utf8 to get the correct calculations.

Reproduce code:
---------------
$data = "<?xml version='1.0' encoding='iso8859-1'?>\n<data>\n<dummy>????</dummy>\n<row>???data</row>\n</data>\n";
function startElement($parser, $name, $attrs)
{
   global $data;
   if($name != "ROW") return;
   $byte = xml_get_current_byte_index($parser) + 41;
   $ch = substr($data, $byte + 41, 7);
   # The following calculates correct
   # $ch = utf8_decode(substr(utf8_encode($data), $byte, 7));
   echo "$name ($byte): $ch\n";
   exit();
}
function endElement($parser, $name)
{
}
$xml_parser = xml_parser_create();
xml_set_element_handler($xml_parser, "startElement", "endElement");
xml_parse($xml_parser, $data, 1);

Expected result:
----------------
ROW (79): ???d

Actual result:
--------------
ROW (79):