How are NS tracks named or classified?

Hello everyone,

I was looking at an NS timetable, and wondered how tracks are named or classified. Specifically, what makes a track a branch, secondary, lead, running, or industrial track? Did the naming or classifying conventions of the predecessor railroads carry over into the merger, or did NS create a new system?

Regards,
Mark

I could be wrong, so anyone can feel free to correct me. I don't know the answers to everything, but I've picked up a few things from studying lines in my area both during the Conrail era and after the split. From what I've been able to figure out:
Running tracks (or "runners") tend to be a connecting branch between two locations without much of an active customer base - you're primarily running trains from one line to another, such as from a main to a branch where there are active customers.
Industrials tend to be specifically used for serving customers, that is to say a track with the classification of industrial is an area with many customers on it, and that is its only purpose.
Leads are usually very specifically a track that goes into a specific customer's property, or for accessing a yard.
Secondary tracks would be those which aren't quite "mains" but would probably see a fair amount of traffic on a regular basis, or as a bypass for a mainline.
I feel like branches could fall under almost any other classification - secondary, running tracks, industrials, etc.
Think of a tree, where your main line is your trunk, and secondary tracks might be larger branches, with smaller branches (industrials, etc) coming off of them as well.

Not 100% sure if there is an official documentation or convention to this, this is just from my observations.