anchor.diff:  
   %%--------------------------------------------------------------------
   %% Function: delete(Key, List)
  -%%           Key = string(), the name of a field in a sip message 
  +%%           Key = string(), the name of a field in a sip message
   %%           List = keylist record()
   %% Descrip.: remove a entry from keylist record() (#keylist.list)
   %% Returns : keylist record()
  
positive.code: 
  %%--------------------------------------------------------------------
  %% Function: to_lower_list(Keys)
  %%           Keys = list() of string(), the name of a field in a sip 
  %%           message 
  %% Descrip.: convert header key, to a standard format - lowercase and
  %%           verbose string() 
  %% Returns : list() of string()
  %%--------------------------------------------------------------------
  to_lower_list(Keys) ->
  
negative.code: 
  %%--------------------------------------------------------------------
  %% Function: append({Key, NewValueList}, List)
  %%           Key = string(), the name of a field in a sip message
  %%           NewValueList = new entries for keyelem identified by Key
  %%           List = keylist record()
  %% Descrip.: add NewValueList to tail of element (#keyelem.item) in
  %%           List (or create new entry if Key is unkown)
  %% Returns : keylist record()
  %%--------------------------------------------------------------------
  