  Supercooled liquid is described in terms of the theory of defected states of
bond orientational order using the continuous theory of defects. It is shown
that the initiation of a local orientation order leads to the breakdown of the
initial SO(3) symmetry of the theory, as a result the plastic deformation
fields of the linear defects become Abelian. The expressions for linear
dislocation and disclination tensor potentials are derived within the framework
of the quasistationary adiabatic approximation. It is shown that $\alpha
$-relaxation and $\beta $-relaxation of supercooled liquid can be described as
relaxation processes in the disclination and dislocation subsystems
accordingly. Disclination topological moment is proposed to use as an order
parameter at the description of glass transition.
