It starts off as W- followed by some numbers. the numbers that follow have an extra number in it. When I filled in that pink box I had an extra number left. Also, whne I entered my number to check status it told me to enter a valid number.
when I sent my son's 80gb core in to sony, my sr number was also one digit longer. sony cs said to put the last digit outside the last box. although, i don't remember having to check the status, since i got at least 2 emails a day from sony concerning the status of my son's ps3. it was returned within 7 days.