PRR Terminology Question

What was the technical difference between a Branch, a Secondary Track, an Industrial Track, and a Running Track? And who controlled what?

I've collected PRR ETT's for just about fifty years, and I've never encountered any explanation of the rationale on that one.

Just to cite one very confusing instance of Pennsy nomenclature, the Northern Division's Emporium-Erie line was long designated as the "Main Line-Erie", presumably because it represented the former main of the old Philadelphia and Erie, which usually saw less traffic than the Emporium-Buffalo line later designated as the Northern (or Buffalo pre-1956) Division Main.

The Main Line-Erie saw passenger service until sometime in the early 1960's. Yet by that time lake ore traffic was gone, it hosted only one through freight in each direction and much of it was dispatched with the use of unattended Block-Limit Stations. PRR rules and policies appear to be full of contradictions.

There is a Yahoo group dedicated to PRR signalling and a post there might turn up some more relevant info.

I never saw it spelled out either, but as far as I could determine during the years I worked for the PRR it seemed to have shaken out about like this:
Main Track: long enough to be a trunk route, fully signaled (automatic or manual block).
Branch: offshoot of a main line, often very short, fully signaled.
Secondary Track: I was told this was based on an ICC (at that time) definition of a track on which signaling (even Manual Block) was not employed, and speed was quite restricted (that's a small "r"); controlled by a dispatcher.
Running Track: similar to a Secondary Track but controlled by a yardmaster -- often parallel to a main track.
Industrial Track: what other people call a siding, serving a carload customer and maintained by the customer.

Above subject to additions, corrections, and emendations -- I wasn't in the operating department.

The answers can be found in the PRR Rule Book and employee timetables.
The PRR streamlined their operations with rules for secondary and running tracks which were far simpler than the traditional rules that governed main tracks.
Simply stated, they dreamed up a way of running trains without train orders.
The topic has been covered in the PRR Signaling Yahoo Group (one must be a member): http://finance.groups.yahoo.com/group/PRRSignaling/
And here's a link to a PRR Rule Book: http://broadway.pennsyrr.com/Rail/Prr/B ... k1956.html ...see Rules 110, 112, and 271-273.
Timetable nomenclature was informative but did not govern operations; the formal lists of main, secondary and running tracks, along with the type of signalling that may be in effect, were in the back of the timetable.