Click on the chart above to enlarge. The Wagenstandanzeiger chart shows major trains which stop durinng the day at this DB Bahn platform. It shows the scheduled time, train identifier, its destination and the direction it is heading. Look closer and you see compartment numbers of each train and above them the zones (A, B, C) where they will stop.
Each platform has signs (see below of a station in Berlin and you see zone D clearly and zone C in the distance) so passengers can congregate near their appropriate zone.
Big Deal you say?
Every ticket issued by DB Bahn, even months prior, indicates the train number, platform number, compartment number and your seat numbers within that compartment. It helps organize millions of passengers who show up from many countries many without any knowledge of German or the train system in the country. It saves DB Bahn from having countless staff to ensure smooth boarding in the few minutes a train stops.
Now, think this is a unique chart for each platform in each station in the system. It is prepared months in advance for a system where trains amazingly go in both directions on each track. Think of the millions of routes and stops that are customized in each chart. Think of all the complexity it masks.
Admire its beauty while you wait for your train. Just be aware many of your fellow passengers will check and recheck it often so don’t monopolize the view :)