As Warwick suggested, do you mean shirt size on the sign up page, as opposed to number?
I think they're just after shirt number. Usually the TD's ask some random question like
What star sign are you ? , How many pieces of red clothing do you have ? Favourite Fruit ? What is the air-speed velocity of an unladen swallow? .... Well maybe not the last one.
I dont think they'll be making up shirts but I'm happy to be proven wrong by Tom.