I am interested in the appearance of the targets for turnouts on spur lines and yards in the 1950's and 1960's. I have a faint memory of a yellow round target that was perpendicular to the track when the turnout was open and parallel to the track when it was open (i.e. you couldn't see it). This was in the yard in Jasper. But my memory may be suspect. Was there any particular standard for such targets? Is there a web site or reference where I could read about this? Any comments or suggestions would be appreciated.