This is a really interesting idea. I like the juxtaposition of the fact a train goes only on a set track through known lands, and a cartographer discovers new lands that wouldn’t have trains yet, so in my mind, the train would deliver the mapmaker to the edge of the known world to continue making maps of the unknown land so it can be made known.
Google forks Linux to make a mobile operating system, stripping out lots of familiar FOSS software and licensing requirements and replacing it with their own. Also it’s written in java.