The XML event handlers defined are: PHP function to set handler Event description xml_set_element_handler Element events are issued whenever the XML parser encounters start or end tags. There are separate handlers for start tags and end tags. xml_set_character_data_handler Character data is roughly all the non-markup contents of XML documents, including whitespace between tags. Note that the XML parser does not add or remove any whitespace, it is up to the application (you) to decide whether whitespace is significant. xml_set_processing_instruction_handler PHP programmers should be familiar with processing instructions (PIs) already. <?php ?> is a processing instruction, where php is called the "PI target". The handling of these are application-specific, except that all PI targets starting with "XML" are reserved. xml_set_default_handler What goes not to another handler goes to the default handler. You will get things like the XML and document type declarations in the default handler. xml_set_unparsed_entity_decl_handler This handler will be called for declaration of an unparsed (NDATA) entity. xml_set_notation_decl_handler This handler is called for declaration of a notation. xml_set_external_entity_ref_handler This handler is called when the XML parser finds a reference to an external parsed general entity. This can be a reference to a file or URL, for example. See the external entity example for a demonstration. xml_set_start_namespace_decl_handler This handler is called for the start of a namespace declaration. xml_set_end_namespace_decl_handler This handler is called for the end of a namespace declaration. Note that this event is not triggered by libXML.