1: const string documentRelationshipType = "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument";

   2: const string wordDOCXContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml";

   3: string docName = @"c:\test9\1nameis.dotx";

   4: Package wdPackage = Package.Open(docName, FileMode.Open, FileAccess.ReadWrite);

   5: PackagePart documentPart = null;

   6: Uri documentUri = null;

   7:  

   8: //  Get the main document part (document.xml).

   9: foreach (System.IO.Packaging.PackageRelationship relationship in wdPackage.GetRelationshipsByType(documentRelationshipType))

  10: {

  11:     documentUri = PackUriHelper.ResolvePartUri(new Uri("/", UriKind.Relative), relationship.TargetUri);

  12:     documentPart = wdPackage.GetPart(documentUri);

  13:     //  There is only one document.

  14:     break;

  15: }

  16:  

  17: XmlDocument xdoc = new XmlDocument();

  18: xdoc.Load(documentPart.GetStream());

  19:  

  20: //  Delete the document part and its relationship part.

  21: wdPackage.DeletePart(documentPart.Uri);

  22:  

  23: //  Create new document and relationship parts using the correct content types.

  24:           

  25: documentPart = wdPackage.CreatePart(documentUri, wordDOCXContentType);

  26: xdoc.Save(documentPart.GetStream(FileMode.Create, FileAccess.Write));

  27: wdPackage.Close();

  28:  

  29: string newFileName = Path.GetDirectoryName(docName) + @"\" + Path.GetFileNameWithoutExtension(docName) + ".docx";

  30: //  If the new file exists, delete it. You might

  31: //  want to make this code less destructive.

  32: if (File.Exists(newFileName))

  33: {

  34:     File.Delete(newFileName);

  35: }

  36: File.Move(docName, newFileName);

  37: