Trying to differentiate between two variables

OK! You are making me feel better, @K.Daube. I'll work through your links and will report back if I make a break-through. Perhaps you were the only one in the world who knew it existed, until my student asked about it? LOL 

As always, thank you!

~Barb

OK, @pulkitn, I'm going to try roping you in since you're the developer who most often pops into this forum. Just what does the <$chaptertitlename> system variable do, how, and why is it included? Someone apparently left that out of the documentation.

I knew you were going to be the one to respond to this, even as I posted the question, @K.Daube! 😊 

And thank you. But I've read the help entry repeatedly and I'm still completely unclear how to use it. I understand the words—and keystroked it—but I don't see what the practical application is. Do you?

I made a folder, dragged in a few files. Used properties to add a file to the folder that was not in my book. When I open all files in book, or save as pdf the associated file is included as if it were directly in the book list. Ok. I'm unclear why I would do that. But even after, when I add the variable, it still behaves exactly like the Filename (short) variable. 

~Barb