Comments on STRING

Hello,

  Regadring the string in sparql, if we have the following DATA:

DATA:
@prefix foaf:       <http://xmlns.com/foaf/0.1/> .

_:a  foaf:name       "Robert"@EN.
_:a  foaf:name       "Roberto"@ES.
_:a  foaf:mbox       <mailto:bob@work.example> .

And the following query:

PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?mbox
 WHERE { ?x foaf:name  ?name ;
            foaf:mbox  ?mbox .
         FILTER ( lang(?name) = "es" ) }

I think that this query fails to match "es" in the FILTER. 

And what about if we have 'ES' or '''ES''',  does the query match the DATA or 
not?
Should we transform the literals to a normal form?


Best regards,
Faisal
INRIA Rhône-Alpes