Trek Bike Frame number, etc

I need to find out my Trek 4300's frame number for insurance purposes.
On the underside of the bottom bracket, I found 3 set of numbers of the
following format:
(Alphabet as shown below, with n denoting a numeric digit)

nnnnUnnn (laid out horizontally)

WTU
nnnSnnnnX (laid out vertically on the left)

TBI-nnnn
GSnZnnnn (laid out vertically to the right)

Which is the frame number? What are the other two numbers???