I've not booked "best rate" using the voucher yet, but I was able to get into the best rate site without any problems. Here is how the information was formatted on the back of the voucher, and how I had to enter it. BTW, L=letter , #=number , and _ = space
On my Voucher, received today :
LLL##__ ##/##/##_LLL:###_Tr:___#__##
The group LLL## was not used as input for the site.
Entered in the site was this, in the following format:
From the pulldown menu , the three letter corresponding to the second LLL group + MM + DD + YY + the 2 digit # signified by the last 2 #.
I think the example given in MagicKingdom05's message where it shows the last group as (#-####) may mean that that group is composed of one to four digits. In my case , I entered 2 digits and got in on my second try.