Index: TWiki/TWikiPreferences.txt
===================================================================
--- TWiki/TWikiPreferences.txt	(revision 4669)
+++ TWiki/TWikiPreferences.txt	(working copy)
@@ -1,7 +1,8 @@
-%META:TOPICINFO{author="TWikiContributor" date="1111929255" format="1.0" version="$Rev$"}%
-
+%META:TOPICINFO{author="MattWilkie" date="1121808440" format="1.1" version="1.2"}%
 ---+!! <nop>%WIKITOOLNAME% Site-Level Preferences
 
+| This [[%TWIKIWEB%.%TOPIC%]] is the as-shipped site-level preferences, however the [[%MAINWEB%.%TOPIC%]] prefs topic has overrride priority and should be used for local customisations. This allows for easier upgrades as you don't need to worry about the shipped preferences clobbering yours.|
+
 The following are __site-level__ settings that affect all users in all webs on this TWikiSite. They can be selectively overwritten on the __individual web level__ (see %WEBPREFSTOPIC% in each web), __topic level__ (the topic being rendered), and on the __user level__ (create preferences in your user account topic in the %MAINWEB% web, ex: %WIKIUSERNAME%).
 	* %X% *NOTE:* You can lock individual settings at the site or web levels using User & Group Access Control - see section below.
 %EDITPREFERENCES{"TWikiPreferencesForm"}%
@@ -331,3 +332,5 @@
    * Set FINALPREFERENCES = GLOBALFINALTESTPREF1
    * Set FINALPREFERENCES = GLOBALFINALTESTPREF2
 -->
+
+