Zijn alleen-op-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een-een
Hebben alleen schrijf-eienschappen praktische toepassingen?