&reftitle.constants; &extension.constants;

`LIBXML_BIGLINES` (`int`)

- Allows line numbers greater than 65535 to be reported correctly.

  Only available as of PHP 7.0.0 with Libxml >= 2.9.0

`LIBXML_COMPACT` (`int`)

- Activate small nodes allocation optimization. This may speed up your application without needing to change the code.

  Only available in Libxml >= 2.6.21

`LIBXML_DTDATTR` (`int`)

- Default DTD attributes

`LIBXML_DTDLOAD` (`int`)

- Load the external subset

`LIBXML_DTDVALID` (`int`)

- Validate with the DTD

  Enabling validating the DTD may facilitate XML External Entity (XXE) attacks.

`LIBXML_HTML_NOIMPLIED` (`int`)

- Sets HTML_PARSE_NOIMPLIED flag, which turns off the automatic adding of implied html/body... elements.

  Only available in Libxml >= 2.7.7 (as of PHP >= 5.4.0)

`LIBXML_HTML_NODEFDTD` (`int`)

- Sets HTML_PARSE_NODEFDTD flag, which prevents a default doctype being added when one is not found.

  Only available in Libxml >= 2.7.8 (as of PHP >= 5.4.0)

`LIBXML_NOBLANKS` (`int`)

- Remove blank nodes

`LIBXML_NOCDATA` (`int`)

- Merge CDATA as text nodes

`LIBXML_NOEMPTYTAG` (`int`)

- Expand empty tags (e.g. `<br/>` to `<br></br>`)

  This option is currently just available in the domdocument.save and domdocument.savexml functions.

`LIBXML_NOENT` (`int`)

- Substitute entities

  Enabling entity substitution may facilitate XML External Entity (XXE) attacks.

`LIBXML_NOERROR` (`int`)

- Suppress error reports

`LIBXML_NONET` (`int`)

- Disable network access when loading documents

`LIBXML_NOWARNING` (`int`)

- Suppress warning reports

`LIBXML_NOXMLDECL` (`int`)

- Drop the XML declaration when saving a document

  Only available in Libxml >= 2.6.21

`LIBXML_NSCLEAN` (`int`)

- Remove redundant namespace declarations

`LIBXML_PARSEHUGE` (`int`)

- Sets XML_PARSE_HUGE flag, which relaxes any hardcoded limit from the parser. This affects limits like maximum depth of a document or the entity recursion, as well as limits of the size of text nodes.

  Only available in Libxml >= 2.7.0 (as of PHP >= 5.3.2 and PHP >= 5.2.12)

`LIBXML_PEDANTIC` (`int`)

- Sets XML_PARSE_PEDANTIC flag, which enables pedantic error reporting.

  Available as of PHP >= 5.4.0

`LIBXML_XINCLUDE` (`int`)

- Implement XInclude substitution

`LIBXML_ERR_ERROR` (`int`)

- A recoverable error

`LIBXML_ERR_FATAL` (`int`)

- A fatal error

`LIBXML_ERR_NONE` (`int`)

- No errors

`LIBXML_ERR_WARNING` (`int`)

- A simple warning

`LIBXML_VERSION` (`int`)

- libxml version like 20605 or 20617

`LIBXML_DOTTED_VERSION` (`string`)

- libxml version like 2.6.5 or 2.6.17

`LIBXML_SCHEMA_CREATE` (`int`)

- Create default/fixed value nodes during XSD schema validation

  Only available in Libxml >= 2.6.14 (as of PHP >= 5.5.2)