No offence taken but if it was IN ENG it would show E1/E2.
ENG ON SITE is the banner message left after an engineer has exited engineering.
An M series in engineers could show many things but ENG on SITE could be on a second keypad if another was in use, similar to the TS900/2200/2500.
But we are told this is a TS700 so the hypothesis is correct in the first paragraph.
So either set and unset, or enter code and enter then exit user menu or as above enter code and press ESC to reset to time display.
We used to have a game, see who could programme a redcared TS700 the fastest, without errors. We got it down to less than 10 seconds as most defaults are fine, but this included part sets too.
It wont work on the new stuff, the processor does not allow "speed programming" hence I usually used the A to B USB lead and the Laptop. Then you could use the printout for the office documentation.
Or dial into one when on call :P
Alarm, August 2012