/** @var string|null The class to use for the resultant document object. This class must derive from \DOMDocument and may not require any constructor parameters */
/** @var string|null The fallback encoding used when no encoding is provided or can be detected for the document. See https://html.spec.whatwg.org/multipage/parsing.html#determining-the-character-encoding:implementation-defined for guidance */
/** @var bool|null Whether to use the HTML namespace rather than the null namespace for HTML elements. Using the HTML namespace is the correct behaviour, but this has performance and compatibility implications for PHP */
/** @var bool|null Whether to retain processing instructions rather than parsing them into comments as the HTML specification requires. Setting this true will yield non-standard documents */