Right now we have two questions tagged tikz-chains. I was first going to post yet another tagging meta question, but I thought I would be bold and say we do not need a tag for individual TikZ libraries. I would suspect that TikZ experts can answer questions about tikz-chains, and vice versa.
I can't suggest the merge since I don't have a high enough score in the tag to do so (you need a 5 in tag to be merged; my bronze tikz-pgf medal is no good!)