Write the modified document to a stream, eg a FileStream or MemoryStream.
Note that you cannot write more than once on the same document instance. After calling Document.Write() information in this instance can be incorrect.
For signing support you must be sure the underlaying output stream is seekable. If the stream is writable only (eg Response.OutputStream) an exception will be raised.
public Void Write( Stream stream , DocumentWriteMode writeMode )