what does GDA mean

[cavok]

Hi all,
I was wondering if anyone could help with this.
I've just put a deposit on a '03 Impreza WRX.
Apparently it is a UK car and the V5 seems to support this.
However, on the log book it shows GDA next to "variant".
Is this just used to denote the shape in the same way that BMW use E36 and Porsche 993, 996 etc.

I'd be grateful for any advice,
Cheers, Cavok