&reftitle.constants; &extension.constants;

`XML_ERROR_NONE` (`int`)

`XML_ERROR_NO_MEMORY` (`int`)

`XML_ERROR_SYNTAX` (`int`)

`XML_ERROR_NO_ELEMENTS` (`int`)

`XML_ERROR_INVALID_TOKEN` (`int`)

`XML_ERROR_UNCLOSED_TOKEN` (`int`)

`XML_ERROR_PARTIAL_CHAR` (`int`)

`XML_ERROR_TAG_MISMATCH` (`int`)

`XML_ERROR_DUPLICATE_ATTRIBUTE` (`int`)

`XML_ERROR_JUNK_AFTER_DOC_ELEMENT` (`int`)

`XML_ERROR_PARAM_ENTITY_REF` (`int`)

`XML_ERROR_UNDEFINED_ENTITY` (`int`)

`XML_ERROR_RECURSIVE_ENTITY_REF` (`int`)

`XML_ERROR_ASYNC_ENTITY` (`int`)

`XML_ERROR_BAD_CHAR_REF` (`int`)

`XML_ERROR_BINARY_ENTITY_REF` (`int`)

`XML_ERROR_ATTRIBUTE_EXTERNAL_ENTITY_REF` (`int`)

`XML_ERROR_MISPLACED_XML_PI` (`int`)

`XML_ERROR_UNKNOWN_ENCODING` (`int`)

`XML_ERROR_INCORRECT_ENCODING` (`int`)

`XML_ERROR_UNCLOSED_CDATA_SECTION` (`int`)

`XML_ERROR_EXTERNAL_ENTITY_HANDLING` (`int`)

`XML_OPTION_CASE_FOLDING` (`int`)

`XML_OPTION_PARSE_HUGE` (`int`)

- Available as of PHP 8.4.0. When libxml2 < 2.7.0 is used (e.g. on PHP 7.x), this option is enabled by default and cannot be disabled.

`XML_OPTION_TARGET_ENCODING` (`int`)

`XML_OPTION_SKIP_TAGSTART` (`int`)

`XML_OPTION_SKIP_WHITE` (`int`)

`XML_SAX_IMPL` (`string`)

- Holds the SAX implementation method. Can be `libxml` or `expat`.