We've had a number of "how to light trains" discussions over the years, mostly focusing on specific problems. But we've never had a thread (as far as I can find) that worked as a FAQ/sticky on train lighting.  So I'm starting this one as a repository for such posts.  Hopefully we'll get enough content to make it a sticky.   This is really intended to be specific to passenger car interior lights, but additional comments on head/tail lights won't be off topic.  Let's avoid in-depth headl