Hello, I know this has been asked before but when I searched PN, I was inundated with stolen equipment serial numbers which don't help. I'm changing insurance companies and need to inventory my equipment along with the serial numbers. Canon doesn't make this easy! I've been looking at the lens-mount end of the lens and it's not altogether clear what the serial number is and in some cases there are two numbers. For example, on my 17-40mm F/4L, stenciled into the metallic ring is the number 59835. But then there's another number (sort of on the black part) UR0300. I understand that the "URO300" is a date code so that one can determine where and when the lens was made. (U = Utsunomiya, Japan; The second letter, "R", is a year code that indicates the year of manufacture, etc.) However, this doesn't *seem* like a true serial number and if it's not, where the heck is it? On my 500mm f/4L IS lens, the "date code" (US0114) seems to be the *only* number I can find on it anywhere. Is that my lens's serial number and if not, where the heck is it? Does the location vary from lens to lens? Thanks in advance for any advice!