(PHP 4, PHP 5)
xml_set_processing_instruction_handler — Set up processing instruction (PI) handler
   Sets the processing instruction (PI) handler function for the XML parser
   parser.
  
A processing instruction has the following format:
<?
?>
    
parserA reference to the XML parser to set up processing instruction (PI) handler function.
handler
       handler is a string containing the name of a
       function that must exist when xml_parse() is called
       for parser.
      
       The function named by handler must accept
       three parameters:
       
$parser
        , string $target
        , string $data
        )parsertargettarget, contains the PI
           target.
          
         datadata, contains the PI
           data.
          
         
       If a handler function is set to an empty string, or FALSE, the handler
       in question is disabled.
      
Note: Instead of a function name, an array containing an object reference and a method name can also be supplied.
   Returns TRUE on success or FALSE on failure.