a IList
The Signature.ObjectList property uses a collection of System.Security.Cryptography.Xml.DataObject objects to represent the <Object> tag of an XML digital signature.
You can also add a System.Security.Cryptography.Xml.DataObject to this collection using the Signature.AddObject(DataObject) method.
For more information about XML digital signatures, see the W3C specification at www.w3.org/TR/xmldsig-core/.