Thank you for the reply.
Why would you want to turn off the clock? It is actuallynot running, only a starting time is recorded. Just "start"it again when you need a new clock.
A further suggestion is born or my initial experiment with his function: I started the clock a bit too late, so all the timestamps are off by about 30-40 seconds. Is it (at least in theory) possible to adjust all time stamps in a subtree by the same amount? That would enable me to correct all of my notes in one fell stroke.Of course this is possible, but code for that would need to be written.