array->AppendElement(kNC_Hostname);
nsGlobalHistory::ArcLabelsOut(nsIRDFResource* aSource,                              nsISimpleEnumerator** aLabels){  NS_PRECONDITION(aSource != nsnull, "null ptr");  if (! aSource)    return NS_ERROR_NULL_POINTER;  nsresult rv;  if ((aSource == kNC_HistoryRoot) ||      (aSource == kNC_HistoryByDate)) {    return NS_NewSingletonEnumerator(aLabels, kNC_child);  }  else if (IsURLInHistory(aSource)) {    // If the URL is in the history, then it'll have all the    // appropriate attributes.    nsCOMPtr<nsISupportsArray> array;    rv = NS_NewISupportsArray(getter_AddRefs(array));    if (NS_FAILED(rv)) return rv;    array->AppendElement(kNC_Date);    array->AppendElement(kNC_FirstVisitDate);    array->AppendElement(kNC_VisitCount);    array->AppendElement(kNC_Name);    array->AppendElement(kNC_Hostname);    array->AppendElement(kNC_Referrer);    return NS_NewArrayEnumerator(aLabels, array);  }  else if (IsFindResource(aSource)) {    nsCOMPtr<nsISupportsArray> array;    rv = NS_NewISupportsArray(getter_AddRefs(array));    if (NS_FAILED(rv)) return rv;    array->AppendElement(kNC_child);    array->AppendElement(kNC_Name);    array->AppendElement(kNC_NameSort);        return NS_NewArrayEnumerator(aLabels, array);  }  else {    return NS_NewEmptyEnumerator(aLabels);  }}