From: stephen@sprunk.org   
      
   On 15-Jan-16 23:48, Larry Sheldon wrote:   
   > I have come to the conclusion that I really don't what a "home   
   > signal" is and the on-line dictionaries don't seem a to match (or   
   > "support") any of the things I thought--whatever that might mean.   
      
   Simply put, a home signal is a signal that protects an interlocking, and   
   it is typically controlled by a human setting routes.  A distant signal   
   protects a home signal.  In contrast, a block signal reflects only track   
   occupancy ahead; they are completely automatic.   
      
   What makes it confusing is that, today, most home and distant signals   
   _also_ act as block signals for the selected route.  In some systems,   
   home signals and distant/block signals have mutually exclusive aspects,   
   while in others, home/distant signals use block signal aspects for the   
   main route but unique aspects for the diverging route(s).   
      
   One critical distinction is that an all-red aspect on a home signal   
   always indicates "stop and stay" whereas the same all-red aspect on a   
   distant/block signal usually indicates "stop and proceed at restricted   
   speed"; this obviously requires a clear means to differentiate the two,   
   e.g. the presence of a number plate or the number of signal heads.   
      
   S   
      
   --   
   Stephen Sprunk         "God does not play dice."  --Albert Einstein   
   CCIE #3723         "God is an inveterate gambler, and He throws the   
   K5SSS        dice at every possible opportunity." --Stephen Hawking   
      
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