Recently we setup 2 new IBM Domino servers and today I found an issue related to how we display time in our application. The 12-hours format was used (with AM or PM). I've checked OS date settings and they were right so I started to google and found out that in order to change locale settings to 24-hours you have either update notes.ini with a ClockType variable or change register.
I went with notes.ini (feel more safe with it). Below few variables that control date/time format output.
DateOrder=YMD DateSeparator=. TimeSeparator=: CLOCKTYPE=24_HOUR
It is also possible for windows OS to change register (but I personally do not like that).
HKEY_USERS\.DEFAULT\Control Panel\International\iDate HKEY_USERS\.DEFAULT\Control Panel\International\iTime HKEY_CURRENT_USER\Control Panel\International\iDate HKEY_CURRENT_USER\Control Panel\International\iTime
You may find more information about it in article Timely information in NOTES.INI