The principal aim of this paper is to state and prove the so-called Reid ro
undabout theorem for the symplectic dynamic system (S) z(Delta) = S(l)z on
an arbitrary time scale T, so that the well known case of differential line
ar Hamiltonian systems (T = R) and the recently developed case of discrete
symplectic systems (T = Z) are unified. We list conditions which are equiva
lent to the positivity of the quadratic functional associated with (S), e.g
, disconjugacy tin terms of no focal points of a conjoined basis) of (S), n
o generalized zeros for vector solutions of (S), and the existence of a sol
ution to the corresponding Riccati matrix equation. A certain normality ass
umption is employed. The result requires treatment of the quadratic functio
nals both with general and separated boundary conditions.