(PHP 8 >= 8.4.0)
Each Dom\Document has a doctype
attribute whose value is either null
or a Dom\DocumentType object.
This is the modern, spec-compliant equivalent of DOMImplementation.
The public identifier of the external subset.
The system identifier of the external subset. This may be an absolute URI or not.
The name of DTD; i.e., the name immediately following the
DOCTYPE
keyword.
The internal subset as a string, or null
if there is none. This
does not contain the delimiting square brackets.