They're called "Named Markers". If you search the forum, there's plenty around including in the various "getting started" folders in the Routebuilding and RBC forums.
http://ftp.uktrainsim.com/viewtopic.php ... 4#p1327077 is one.
These can be set up using RW Tools, though personally I take the numbers from Google, copy a default bin file and edit it manually and point the route properties files to it.
The markers also appear if you're in the scenario editor - click on the world symbol in the top of the screen "fly down", chose your destination and press the arrow key and you will fly there.
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