Originally Posted by janey

Hmmm...looking at the stickers I'm removing, there is taupe colored sticker (likely from a trip in 2008) that has "M9" handwritten on it, a yellow sticker with "N 24 Feb 09", and a black sticker with "24 Feb 10 S" written on it (yes, I was in Paris the exact same week in 2009 and 2010). All of them are printed with "Security ICTS." So it looks like there's a different color each year, although the M9 could be some super-secret code.