Many of you have used this site's Canon Lens Date Code Lookup
page to determine when your Canon lens was manufactured. I regret to inform you that this ability may be disappearing from the Canon scene.
I have been getting reports (thanks for them) for a while now that the latest Canon EF 70-200mm f/2.8 L IS II USM Lenses
are being produced without the date code and with a longer 10-digit serial number. Chuck Westfall (Canon USA) has confirmed that this is indeed the case, but he was not yet able to determine if the longer serial number may have the date code embedded in it.
I welcome any new information in this regard - and will share with you anything I learn. Stay tuned!