@dougal1957 Sure, using a low standby temperature as a substitute for turning the heater off will do the trick in most situations. However, I can think of a few corner cases where going to the actual off-state may be preferred:
If I do not want to overwrite the standby-temp, for example to make it easy to manually switch it on again
To make it clear in the web interface that the heater is off
To ensure that the heater does not start even if the temp-sensor says it is below zero.
Note that it is already possible to turn the heater off with "M140 S-274". My suggestion is simply to move this functionality to M144 where it (in my opinion) belongs, since M144 is all about switching the bed heater state.
/Ö