Hi,
I'm about to write a book using a structure. The desire is to get this like
contents of the table of contents :

Chapter 1 Title

  Part 1  Title

   1.
   2.


  Part 2  Title

   1.
   2.

  Part 3  Title

   1.
   2.


Chapter 2 Title

  Part 1 Title

  1.
  2.


  Part 2 Title

  1.
  2.

Part 3 Title

  1.
  2.

##########################
lesson.tex


\project manual

\startproduct lesson

\startfrontmatter
  \component   titlepage
  \component   contents
\stopfrontmatter

\startbodymatter
  \component  chapter-1
  \component  chapter-2
\stopbodymatter

\stopproduct

############################

chapter-1.tex

\startcomponent chapter-1

  \component activities-1
  \component synthesis-1
  \component training-1

\stopcomponent

#############################

Thanks,
Fabrice