OS is the railroad term for On Station. It refers to when a train accepts a signal, or occupies what is referred to by Signals and Communications as the "OS" Track. In dark territory, it is also a "track release" location. The RTC may ask for an "OS" by Mile 25. When the train calls to report they are entirely by Mile 25, the RTC can release the section of track the train has operated over. In Old School Railroading, OS referred to "On Sheet", where a train sheet was used to report times that trains had reported over specific locations.
Nil Per Os - Nothing By Mouth
The Transcontinental Railroad
OS : Over Seas Conus : Continental United States
Operating System
Milestone
Operating System.
LOLlipop! And the name of the flick is "Stand by Me"
Thomas And The Magic Railroad
oversizes
It means shortcut.
"Anos tienes" translates to "How old are you?" in English.
Operating System (In the context of an actual map, OS stands for Ordnance Survey, the national mapping agency for Great Britain.)