Where Great Britain's electricity is coming from, right now.
An Electricity Margin Notice (EMN) is NESO asking generators and suppliers for more spare capacity over the next few hours. It's an early warning used a handful of times a year, usually on still, cold or high-demand evenings. It doesn't mean power cuts are likely.
Emergency instructions, emergency help over interconnectors and other NESO notifications. Routine IT-outage and SO-to-SO price notices are left out.
Frequency should stay between 49.8 and 50.2 Hz in normal operation, and 49.5 to 50.5 Hz is the statutory limit. Demand is Elexon's initial national demand outturn against NESO's latest national demand forecast for each half-hour, published shortly before it. Interconnector flows are 5-minute averages. Times are UK time.