  In this paper, we study the local exact boundary controllability of entropy
solutions to a class linearly degenerate hyperbolic systems of conservation
laws with constant multiplicity. The authors prove the two-sided boundary
controllability, one-sided boundary controllability and two-sided
controllability with less controls, by applying the strategy used originally
for classical solutions with essential modifications. Our constructive method
is based on the well-posedness of semi-global solutions constructed by the
limit of $ \e $-approximate front tracking solutions to the mixed
initial-boundary value problem with general nonlinear boundary conditions and
some further properties on both $ \e $-approximate front tracking solutions and
entropy solutions.
