Putale mentioned this in another thread about the "empty emoticons".
Example: :mrgreen: does not create an emoticon even though I just clicked it off the Smilies menubox. However " :D " is not listed anywhere in the Smiley list, but creates what :mrgreen: was supposed to show! I can list more, however it seems the forums are referencing a different Smiley code than the one presented to the user to work with. :)