in which belgium city are the headquarters of the commission internationale permanente pour l'epreuve des armes à feu portatives ?
select distinct var_uri where brack_open dbr_Commission_Internationale_Permanente_pour_l'Epreuve_des_Armes_à_Feu_Portatives dbo_headquarter var_uri sep_dot var_uri dbo_country dbr_Belgium sep_dot brack_close