diff --git a/editions/tw5.com/tiddlers/styleguide/Spelling.tid b/editions/tw5.com/tiddlers/styleguide/Spelling.tid
index eceb59962..92c16086e 100644
--- a/editions/tw5.com/tiddlers/styleguide/Spelling.tid
+++ b/editions/tw5.com/tiddlers/styleguide/Spelling.tid
@@ -5,7 +5,7 @@ tags: [[Improving TiddlyWiki Documentation]]
 
 Because ~TiddlyWiki is of British origin, its English documentation uses [[British spelling in preference to US spelling|http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences]].
 
-Words like <<.word customise>> are spelled <<.word -ise>>, not <<.word -ize>>.
+Words like <<.word customise>> are spelled <<.word -ise>>, not <<.word -ize>>. Words like <<.word colour>> will also be spelled using UK English unless they are being used for reserved words in code, such as in CSS or JavaScript.
 
 Standard technical acronyms are written in upper case, without dots: <<.word HTML>>, not <<.word html>> or <<.word H.T.M.L.>>