Line
Line turns up in 2 fields: railroad, automotive. Here is what it means to the people in each one.
Line in railroad
To throw a switch so it routes a train or car onto the intended track.
Switches are lined by hand at a switch stand or by the dispatcher through power switches, and crews say a switch is lined for the main or lined for the siding. Before a move the crew checks that every switch is lined and locked with its points fitting tight, and after hand-throwing a main track switch they report it restored to normal position. A switch left lined the wrong way is the classic cause of trains entering occupied tracks.
"Line us into 6 and get the derail, then call me back when you're clear and I'll start the shove."
Line in automotive
The optimal path a driver takes through a corner to maintain maximum speed and stability.
The line, or racing line, is the geometric path a driver chooses through a corner or sequence of corners. A proper line uses the entire width of the track, starting at the outside edge, clipping the inside apex, and tracking back to the outside on the exit to carry the highest possible speed with the least steering input.
"You're turning in too early on turn four and it's completely ruining your line for the straight."