Answer:
Lap length design is performed according to DIN EN 1992‑1‑1, Section 8.7.3 or Section 10.9.6.3 for block and bucket foundations with the profiled bucket surface.
You can optionally deactivate the design using the [Details …] button.
An example of the lap length calculation for a bucket foundation can be found in the RF‑/FOUNDATION Pro manual, which you can download using the following link, or open it directly in the add-on module by pressing the [F1] key.