//// Create the retrieve request and define the object and properties we want to retrieve
        $rr = new ExactTarget_RetrieveRequest();
        $rr->ObjectType = "List";
        $rr->Properties =  array();
        $rr->Properties[] = "ID";
        $rr->Properties[] = "ListName";
        $rr->Properties[] = "Category";
        $rr->Properties[] = "Type";
        $rr->Options = NULL;

    //// Set a simple filter part to retrieve the list with a specific ID
    $filter1 = new ExactTarget_SimpleFilterPart() ;
    $filter1->Property= "ListName";
    $filter1->SimpleOperator=ExactTarget_SimpleOperators::notEquals;
    $filter1->Value=array("");   //the id of the list you want to retrieve