The Tacho time measures the time the engine has run over a predetermined RPM and therefore gives a reasonably accurate time for engine overhaul purposes. Some regard it as a measure of airborne time however; if you do a lot of PFLs it will under-read. It counts in minutes. To convert this to flight time, brakes off to brakes on, you need to add time and this could be a simple addition of 10 minutes or the addition of a percentage to the tacho reading. At the end of the day the most accurate time is off your watch.
22.0-22,7 is 0.7 hours Tacho time which equates to about 0.9 hours flight time which you log.