let parse_pref_labels s =
List.map (fun s' ->
match Pcre.split ~rex:eq_regexp s' with
|[v] when (Pcre.pmatch ~rex:di_regexp v) -> ("v",v)
|[v] when (Pcre.pmatch ~rex:al_regexp v) -> ("a",v)
|[l;v] -> (l,v)
|_ -> fatal "To many '=' in label %s" s
) (Pcre.split ~rex:comma_regexp s)