The Pittsburgh Mainline has implemented Paper Signals as a means of track authority on the mainline. This was done based off a well-done article by Bruce Carpenter in the April 2017 Model Railroader. Please see below for various documents pertaining to this information.
Handout for Paper Signal Presentation
Abbreviated Chart of PRR Aspects
Chart of Signal Progressions
The following documents are PDFs of the CAD drawings of PRR Position Light Signals used for all the paper signals on the PML. Each PDF is a full sheet of one signal aspect.
282 Approach Medium
283 Medium Clear
286 Medium Approach
B&O Color Position Light Signals
First set of B&O Aspects - Provided by Keith Devault
Second Set of B&O Aspects - Provided by Keith Devault
Meaning chart - Provided by Keith Devault
B&O Train Orders
B&O Form 19 Train Orders for Crews
B&O Order Book for Dispatcher