In regards to the tack boards, the large ones on the car doors were usually for shippers information and fragile or "Do Not Hump" signs. The smaller tack boards on the side sills were for clean out tags, shop tags, or weigh cards. As to the chalk marking, we called them pool marks and were used by car inspectors to show that that car had been inspected at a certain date by a particular inspector. These marks were at the ends of the cars and had a cross thrrough them. You could also leave a note to another inspector as to stop bleeding the cars at that point or to have a second look at a possible problem with that car. I also would chalk an arrow pointing to the bleed rod to make it easier to see at night. Later we used white spray paint for this and also to paint the tops of the angle cock handles for the same reason.