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.