xml_set_processing_instruction_handler Set up processing instruction (PI) handler boolxml_set_processing_instruction_handler resourceparser callbackhandler Sets the processing instruction (PI) handler function for the XML parser parser. handler is a string containing the name of a function that must exist when xml_parse is called for parser. A processing instruction has the following format: <?target data?> You can put PHP code into such a tag, but be aware of one limitation: in an XML PI, the PI end tag (?>) can not be quoted, so this character sequence should not appear in the PHP code you embed with PIs in XML documents. If it does, the rest of the PHP code, as well as the "real" PI end tag, will be treated as character data. The function named by handler must accept three parameters: handler resourceparser stringtarget stringdata parser The first parameter, parser, is a reference to the XML parser calling the handler. target The second parameter, target, contains the PI target. data The third parameter, data, contains the PI data. If a handler function is set to an empty string, or &false;, the handler in question is disabled. &true; is returned if the handler is set up, &false; if parser is not a parser. ¬e.func-callback;