TFileName fileName = <name of the file to be checked>
  TUid uid;
  TDataType recData;

  CApfMimeContentPolicy *ccp = CApfMimeContentPolicy::NewLC();

  if (ccp->IsDRMEnvelope( fileName ))	
	{
     // Whatever needs to be done if file is DRM envelope.
	}

  // Check file extension.	
  TParse parser;
  parser.Set(fileName, NULL, NULL);
  if (IsClosedExtension(parser.Ext()))
	{
    // Do what needs to be done if closed content.
	}

  iLs.AppForDocument(fileName, uid, recData);  // Get MIME type for file.

  if (ccp->IsClosedType(recData.Des())   // Check if this mime type is closed.
	{
     // Whatever needs to be done if type is closed.
	}
	
  // Or you can achieve same result calling a convinience function
  // which combines all the steps above:
  if (cpp->IsClosedFileL( fileName );
 	{
    // Do whatever has to be done if file is closed.	
	}

  // Don't forget to clean up.
	CleanupStack::PopAndDestroy();  // ccp