# Event Handlers

The XML event handlers defined are:

Supported XML handlers
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.