If this options is set the static safety is calculated based on maximal contact stress. For ball bearings is used, for roller bearings is used, so that the safety factor is proportional to the load. The permissible stress is based on (ISO 76, 2006).
If the option is not set, the static safety factor is calculated based on maximum rolling element load and Qmax in ( ISO/TR 10657, 1991).
For ball bearings both options usually show the same results, but for roller bearings edge stresses are only considered if the static safety factor is based on stresses.