You can define various spare part indicators in this menu option.
The spare part indicator identifies BOM items as spare parts in production BOMs. You can create lists of spares on the basis of this indicator.
You can classify spares on the basis of the spare part indicator (for example, A spares, B spares and so on, and a country-specific classification of spares is possible similar to this).
The spare part indicator is not needed for maintenance BOMs, as these consist solely of spare parts.