function listCategory($base, $category, $info = false, $channel = false)
    {
        if ($info == false) {
            $url = '%s'.'c/%s/packages.xml';
        } else {
            $url = '%s'.'c/%s/packagesinfo.xml';
        }
        $url = sprintf($url,
                    $base,
                    urlencode($category));

        // gives '404 Not Found' error when category doesn't exist
        $packagelist = $this->_rest->retrieveData($url, false, false, $channel);
        if (PEAR::isError($packagelist)) {
            return $packagelist;
        }
        if (!is_array($packagelist)) {
            return array();
        }

        if ($info == false) {
            if (!isset($packagelist['p'])) {
                return array();
            }
            if (!is_array($packagelist['p']) ||
                !isset($packagelist['p'][0])) { // only 1 pkg
                $packagelist = array($packagelist['p']);
            } else {
                $packagelist = $packagelist['p'];
            }
            return $packagelist;
        }

        // info == true
        if (!isset($packagelist['pi'])) {
            return array();
        }

        if (!is_array($packagelist['pi']) ||
            !isset($packagelist['pi'][0])) { // only 1 pkg
            $packagelist_pre = array($packagelist['pi']);
        } else {
            $packagelist_pre = $packagelist['pi'];
        }

        $packagelist = array();
        foreach ($packagelist_pre as $i => $item) {
            // compatibility with r/<latest.txt>.xml
            if (isset($item['a']['r'][0])) {
                // multiple releases
                $item['p']['v'] = $item['a']['r'][0]['v'];
                $item['p']['st'] = $item['a']['r'][0]['s'];
            } elseif (isset($item['a'])) {
                // first and only release
                $item['p']['v'] = $item['a']['r']['v'];
                $item['p']['st'] = $item['a']['r']['s'];
            }

            $packagelist[$i] = array('attribs' => $item['p']['r'],
                                     '_content' => $item['p']['n'],
                                     'info' => $item['p']);
        }

        return $packagelist;
    }