The number of section levels used in the documentation is too high: We are
currently using five levels in some places. We should not use more than three or
four levels. Also, the TAG could benefit from a large re-structure.
Created attachment 762 [details]
Document structure graphs per file
This is a hierarchical representation of the TAG structure, divided per file. All book, part, chapter, appendix and sect1-4 elements along with their titles are represented in these structures.