  Using a more accurate approximation than that applied by Lee--Oehme--Yang we
show that the interpretation of the tests measuring the difference between the
$K_{0}$ mass and the ${\bar K}_{0}$ mass as the CPT--symmetry test is wrong. We
find that in fact such tests are tests for the existence of the hypothetical
interaction allowing the first order $|\Delta S| = 2$ transitions $K_{0}
\rightleftharpoons {\bar K}_{0}$.
