diff --git a/rss/file.php b/rss/file.php
index 2eab98423d2..4f59eb0d238 100644
--- a/rss/file.php
+++ b/rss/file.php
@@ -1,70 +1,91 @@
-<?PHP
-    //This file returns the required rss feeds
-    //The URL format MUST include:
-    //    context: the context id
-    //    user:   the user id
-    //    name:   the name of the module (forum...)
-    //    id:     the id (instance) of the module (forumid...)
-    //If the course has a password or it doesn't
-    //allow guest access then the user field is
-    //required to see that the user is enrolled
-    //in the course, else no check is performed.
-    //This allows to limit a bit the rss access
-    //to correct users. It isn't unbreakable,
-    //obviously, but its the best I've thought!!
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
-// disable moodle specific debug messages and any errors in output
+/**
+ * rss/file.php - entry point to serve rss streams
+ * 
+ * This script simply checks the parameters to construct a $USER
+ * then finds and calls a function in the relevant component to 
+ * actually check security and create the RSS stream
+ *
+ * @package   moodlecore
+ * @copyright 1999 onwards Martin Dougiamas  http://moodle.com
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+
+// Disable moodle specific debug messages and any errors in output
 define('NO_DEBUG_DISPLAY', true);//comment this out to see any error messages during RSS generation
 
-// session not used here
+// Sessions not used here, we recreate $USER every time we are called
 define('NO_MOODLE_COOKIES', true);
 
 require_once('../config.php');
 require_once($CFG->libdir.'/filelib.php');
 require_once($CFG->libdir.'/rsslib.php');
 
-//Check RSS feeds are enabled
+// RSS feeds must be enabled site-wide
 if (empty($CFG->enablerssfeeds)) {
     debugging('DISABLED (admin variables)');
-    rss_not_found();
+    rss_error();
 }
 
-$lifetime = 3600;  // Seconds for files to remain in browser caches - 1 hour
-$filename   = 'rss.xml';
 
+// All the arguments are in the path
 $relativepath = get_file_argument();
 if (!$relativepath) {
-    rss_not_found();
+    rss_error();
 }
 
-// extract relative path components
+
+// Extract relative path components into variables
 $args = explode('/', trim($relativepath, '/'));
 if (count($args) < 5) {
-    rss_not_found();
+    rss_error();
 }
 
 $contextid   = (int)$args[0];
 $token  = $args[1];
 $componentname = clean_param($args[2], PARAM_FILE);
-//$instance   = $args[3];
 
+
+// Authenticate the user from the token
 $userid = rss_get_userid_from_token($token);
 if (!$userid) {
-    rss_not_authenticated();
+    rss_error('rsserrorauth');
 }
+
 $user = get_complete_user_data('id', $userid);
 session_set_user($user); //for login and capability checks
 
+
+// Check the context actually exists
 $context = get_context_instance_by_id($contextid);
 if (!$context) {
-    rss_not_found();
+    rss_error();
 }
 $PAGE->set_context($context);
 
+
+// Work out which component in Moodle we want (from the frankenstyle name)
 $componentdir = get_component_directory($componentname);
 list($type, $plugin) = normalize_component($componentname);
 
-//this will store the path to the cached rss feed contents
+
+// Call the component to check/update the feed and tell us the path to the cached file
 $pathname = null;
 
 if (file_exists($componentdir)) {
@@ -72,30 +93,26 @@ if (file_exists($componentdir)) {
     $functionname = $plugin.'_rss_get_feed';
 
     if (function_exists($functionname)) {
-        //$pathname will be null if there was a problem or the user doesn't have the necessary capabilities
-        //NOTE the component providing the feed should do its own capability checks
+        // $pathname will be null if there was a problem (eg user doesn't have the necessary capabilities)
+        // NOTE:the component providing the feed must do its own capability checks and security
         $pathname = $functionname($context, $args);
     }
 }
 
-//Check that file exists
+
+// Check that file exists
 if (empty($pathname) || !file_exists($pathname)) {
-    rss_not_found();
+    rss_error();
 }
 
-//Send it to user!
-send_file($pathname, $filename, $lifetime);
+// Send the RSS file to the user!
+send_file($pathname, 'rss.xml', 3600);   // Cached by browsers for 1 hour
 
-function rss_not_found() {
-    /// error, send some XML with error message
-    global $lifetime, $filename;
-    send_file(rss_geterrorxmlfile(), $filename, $lifetime, false, true);
-    die();
+
+/*
+ * Sends an error formatted as an rss file and then dies
+ */
+function rss_error($error='rsserror', $filename='rss.xml', $lifetime=0) {
+    send_file(rss_geterrorxmlfile($error), $filename, $lifetime, false, true);
+    exit;
 }
-
-function rss_not_authenticated() {
-    global $lifetime, $filename;
-    send_file(rss_geterrorxmlfile('rsserrorauth'), $filename, $lifetime, false, true);
-    die();
-}
-