Yep. Vertical clutch on a column wheel. So it can be run continually without a major drop in amplitude so it shouldn’t gain much time.
Chronographs with independent drive trains (zenith defy 21 chrono, and JLC Duometre) and those with intelligent designs to separate the power supply to the chronograph and regular timekeeping (FPJ centrigraphe) are the only ones with zero drop in amplitude.
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Guys — I know that running the chrono function continuously is fine on some watches and not on others, depending on the chrono mechanism at issue. (I think I know how to use the terms “lateral clutch” and “column wheel” correctly, but I won’t risk it here...