You can make and manage multiple time systems other than usual time system with AM/PM, 12 hours, 60 minutes and 60 seconds freely and show dials of clocks for these time systems on iPhone.
You can make a dial of clock without AM/PM and with 24 hours starting 0, a clock rotating counterclockwise for people living Southern Hemisphere and a clock for the universal and rational time system devised in The French Revolution.