Subquadrangles of generalized quadrangles of order (q(2), q), q even

First, we survey the known generalized quadrangles of order (q(2), q), q ev en, including a description of their known subquadrangles of order q. Then. in the case of Tits' generalized quadrangles, we completely classify the s ubquadrangles of order q, while in the case oi. the flock quadrangles we cl assify the subquadrangles of order q which contain the base point. Finally, we determine the full automorphism groups of the Tits generalized quadrang les T-2(O) of order q and T-3(Omega) of order (q, q(2)). (C) 2001 Academic Press.