Yards and "YARD LIMITS" are two different terms.Yards can be any tracks for switching, storing, repairing, classifying trains and equipment. The Yard speed includes "Restricted Speed,(Able to STOP within 1/2 the range of vision), not to exceed 10 (15,20,5) mph" per local or company rule. "YARD LIMITS" is a designated piece of unsignalled main, secondary, running track with some type of radio, phone, written control by a dispatcher, where crews may work industrial, yard or other sidings and use switches, or foul that main (with Dispatcher's permission ). If the Dispatcher KNOWS that track to be CLEAR (nobody fouling and the last crew there having lined and locked all main track switches "normal") he may let you proceed thru "Yard Limits" at normal track speed...If ALL of the above isn't KNOWN...Restricted Speed again. Hope that's clearer, 'cause my typers are tired ! When in doubt, take the safest course. Bob C