<PackageReference Include="System.Xml.XDocument" Version="4.0.11-beta-23409" />

System.Xml.Linq.XDocumentType

public class XDocumentType : XNode
Represents an XML Document Type Definition (DTD).
public string InternalSubset { get; set; }

Gets or sets the internal subset for this Document Type Definition (DTD).

public string Name { get; set; }

Gets or sets the name for this Document Type Definition (DTD).

public string PublicId { get; set; }

Gets or sets the public identifier for this Document Type Definition (DTD).

public string SystemId { get; set; }

Gets or sets the system identifier for this Document Type Definition (DTD).

public XDocumentType(string name, string publicId, string systemId, string internalSubset)

Initializes an instance of the XDocumentType class.

Initializes an instance of the XDocumentType class from another XDocumentType object.