AngleSharp by Florian Rappl

<PackageReference Include="AngleSharp" Version="0.2.1" />

 DOMImplementation

Provides a number of methods for performing operations that are independent of any particular instance of the DOM.
using AngleSharp.DOM.Html; namespace AngleSharp.DOM { public class DOMImplementation : IDOMImplementation { public DocumentType CreateDocumentType(string qualifiedName, string publicId, string systemId) { DocumentType documentType = new DocumentType(); documentType.PublicId = publicId; documentType.SystemId = systemId; documentType.NodeName = qualifiedName; return documentType; } public Document CreateDocument(string namespaceURI, string qualifiedName, DocumentType doctype) { Document document = null; document = ((!(Namespaces.Html == namespaceURI)) ? new Document() : new HTMLDocument()); document.AppendChild(doctype); document.NodeName = (qualifiedName ?? document.NodeName); return document; } public object GetFeature(string feature, string version) { return null; } public bool HasFeature(string feature, string version) { return false; } } }