# Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

`LIBXML_BIGLINES` (int)
  Allows line numbers greater than 65535 to be reported correctly.

  > Note:

  > 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.

  > Note:

  > 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
`LIBXML_HTML_NOIMPLIED` (int)
  Sets HTML_PARSE_NOIMPLIED flag, which turns off the automatic adding of implied html/body... elements.

  > Note:

  > 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.

  > Note:

  > 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>`)

  > Note:

  > This option is currently just available in the DOMDocument::save and DOMDocument::saveXML functions.

`LIBXML_NOENT` (int)
  Substitute entities
  Caution

  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

  > Note:

  > 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.

  > Note:

  > 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.

  > Note:

  > 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

  > Note:

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