Well, I think I can confirm now that CS means controlled siding. Thanks to who I assume is RR.net's own Jersey_Mike, he runs a blog known as The Position Light which is all about signals. I won't repost the entirety of the information in the post here out respect (and copyright laws
) but he made a post earlier this year about a resignaling elsewhere in Georgia but on CSX involving a controlled siding. In the post he says that entry into a controlled siding on CSX is governed by a restricting signal since the siding doesn't have detection. The signal governing entry into the siding in question in Lithonia is a two-headed signal with an upper three-light signal and lower two-light signal. From past observations I know the second head can display at least a red aspect, and I've heard the local switch job call Restricting when they actually entered the siding so presumably the other color on the second head is yellow (could be lunar I guess) so since other aspects with a lower-head showing yellow don't make sense in this particular situation, I think it's reasonable to assume that this is a controlled siding and the CS signs indicate the limits. Thanks to all who responded!
Link to the blog post:
http://position-light.blogspot.com/2013 ... in-3d.html" onclick="window.open(this.href);return false;