Short answer
Level-n of the building block view shall be documented in section 5-n of the building block view, where level-0 (zero) is the context view and level-1 your topmost system whitebox.
Longer answer
See the following diagram.

Level-n of the building block view shall be documented in section 5-n of the building block view, where level-0 (zero) is the context view and level-1 your topmost system whitebox.
See the following diagram.

Practical architecture training, most classes taught by Peter Hruschka and Gernot Starke — the people who created arc42 and maintain this FAQ (dates with other trainers say so) — and solid preparation for iSAQB certifications.
Next dates
All courses and dates: trainings.arc42.org · as of 4 Aug 2026