In reply to Indesign ALL CAPS button: what OT-Features does it apply? What is "desired behavior"?:
Nothing is as challenging as laying out a book though
We each have our affinities, and what one person finds easy another might find effectively impossible. However if you were ever to make a font, especially a text font, especially one that other people would pay good money for, you'd probably change your mind. I think making a tool as opposed to a finished product (especially a static one like a book) is on a higher level of difficulty, at least for most people.
small cap figures should be available too, if you include small caps in a font.
Definitely.
hhp