title_body: Indesign -> Kindlegen -> Kindle flattens TOC? I'd like 4 levels of hierarchy in my Kindle navigational TOC (aka "logical TOC" in Kindle Publishing Guidelines terminology), but when I do this:
  
  1. InDesign CC → File → Export → (choose my nested TOC)
  2. `KindleGen in.epub -o out.azw`
  
  
  the "Kindle for PC" software only shows the first level of headings, effectively flattening out levels 2, 3, and 4. However, I know Kindle for PC can show at least 3 levels, as I see in another Kindle book in my library. 
  
  Interestingly, if I click Kindle Previewer → View → NCX View, I see the nesting properly. Do I need Indesign 6 with the Kindle Export for InDesign CS6?
upvoted_answer: It seems that the NCX is limited to two levels of hierarchy. I tested the actual hardware for the Fire HDX, Kindle, and Kindle Paperwhite. They all had the same results. Kindle for PC only shows one level. Lastly, I realized that the multiple-levels displayed in Kindle for PC (in a separate author's book) worked because the author (apparently) submitted a PDF, not an EPUB.