(PHP 5, PHP 7)
This interface represents a known entity, either parsed or unparsed, in an XML document.
$exclusive
   [, bool $with_comments
   [, array $xpath
   [, array $ns_prefixes
  ]]]] )$uri
   [, bool $exclusive
   [, bool $with_comments
   [, array $xpath
   [, array $ns_prefixes
  ]]]] )
       The public identifier associated with the entity if specified, and
       NULL otherwise.
      
       The system identifier associated with the entity if specified, and
       NULL otherwise. This may be an absolute URI or not.
      
       For unparsed entities, the name of the notation for the entity. For
       parsed entities, this is NULL.
      
       An attribute specifying the encoding used for this entity at the
       time of parsing, when it is an external parsed entity. This is
       NULL if it an entity from the internal subset or if it is not 
       known.
      
       An attribute specifying, as part of the text declaration, the
       encoding of this entity, when it is an external parsed entity. This
       is NULL otherwise.
      
       An attribute specifying, as part of the text declaration, the
       version number of this entity, when it is an external parsed
       entity. This is NULL otherwise.