What to know

• Delegates from 69 countries approve clock changeover after decades of debate – but switch may not take effect for thousands of yearsAfter decades of discussion, quibbling and worrying about clocks in computer systems, the world’s official timekeepers have vote...S1
• In the biggest shakeup for timekeeping in over 50 years, a key vote has severed the connection between the Earth's rotation and modern clocks.S2