Okay here we go. This is a guide for the Clinchfield Railroad. It isn't going to initially be 100% correct due to some bugs in the way the signals work on this line. So let's begin. Here are mile markers. Main line ones are just numbers which show the milage. Branch lines have identifying letters before the number and also are a bit different. Mile 1 Mile 35 N22. This is a branch line but the 22 isn't 22 miles. It's 2. The number scheme on these go N11 / N22 / N33 / etc.... H11 Same thing different branch line.