From SPARQL Working Group
Apologies for the delayed reply.
The error you pointed out is solved in the Last Call working draft version available at http://www.w3.org/TR/2011/WD-sparql11-federated-query-20111117/.
We would be grateful if you would acknowledge that your comment has been answered by sending a reply to this mailing list.
Carlos, on behalf of the SPARQL-WG