  We present a method for the evaluation, at the first level of trigger, of
logical conditions with high time resolution, using the digitized times of fast
signals delivered in the detectors of high rate experiments. We describe a
dead-time-less implementation of this method on a commercial Field Programmable
Gate Array (FPGA). By virtue of its features, the method offers an excellent
solution to the problem of including veto conditions in the first level of
trigger for experiments on rare decays.
