  The paper deals with three topics on coquasitriangular bialgebras. A
characterization of universal r-forms in terms of Yetter-Drinfeld modules is
given. All universal r-forms for the coordinate Hopf algebras of the quantum
groups GL_q(N), SL_q(N), O_q(N) and Sp_q(N) are described. It is well-known
that the square of the antipode of a coquasitriangular Hopf algebra A with
universal r-form r can be expressed by means of the linear functional
f_r(a)=r(a_{(1)}\otimes S(a_{(2)})), a\in A. For the standard compact matrix
groups the functional f_r is related to the Woronowicz modular character
f_{-2}.
