  We propose a novel approach to all-optical frequency standard design, based
on a counterintuitive combination of the coherent population trapping effect
and signal discrimination at the maximum of absorption for the probe radiation.
The short-term stability of such a standard can achieve the level of
10^-14/(\tau)^1/2. The physics beyond this approach is dark resonance splitting
caused by interaction of the nuclear magnetic moment with the external magnetic
field.
