With the info you have given I would have to say that Vicky is right. You can have both a fillet and a groove weld applicable on an outside corner joint. There are many types of welds that it could be, Fillet, bevel-groove, flare-bevel-groove, flare-V-groove, J-groove, Square groove, U-groove, V-groove, plug, slot, spot, seam, projection, and braze. If you have a copy of AWS A3.0-94 terms and definitions look at page 41 Figure 1(B). These are all of the applicable welds given for this type joint. In reality, I think they might mean a square groove weld on the outside corner with no plate prep. The fillet would be placed on the inside corner. Fillet Weld = A weld of approximately triangular cross section joining two surfaces approximately at right angles to each other in a lap joint, T-joint, or corner joint. Groove Weld = A weld made in a groove between the workpieces. - definitions per AWS A3.0-94.
Hope this helps,
John Wright