What are these "rail-style" LEGO pieces? I have acquired several large bags of LEGO - most are the tradition bricks, but what kit are these (see photo) rail-type pieces from? They are identified on the reverse with a letter, such as &quot;E&quot;, and a 1 or 2-digit number. Some of the rails contain small teeth the entire length - some are smooth.
The rails with the &quot;small teeth&quot; are
Part No: 3230a ,  Train, Track Tapered Rail Curved Inside
Part No: 3229a Name: Train, Track Tapered Rail Curved Outside
Part No: 3228a Name: Train, Track Tapered Rail Straight 16L