  Generalizing results by Bryant and Griffiths [Duke Math. J., 1995, V.78,
531-676], we completely describe local conservation laws of second-order
(1+1)-dimensional evolution equations up to contact equivalence. The possible
dimensions of spaces of conservation laws prove to be 0, 1, 2 and infinity. The
canonical forms of equations with respect to contact equivalence are found for
all nonzero dimensions of spaces of conservation laws.
