Same here, commitment to stay is not allowed in the planning stage at all so we allways have to carry alternate fuel except for the isolated aerodrome case (in which case 2 hours of final reserve fuel is needed). German JAR rules as well, and yes JAR is not the same in each country, there are quite a few differences until EASA takes over.
We can use commitment however if enroute under certain conditions (2 separate runways with separate instrument approaches, suitable weather, current and forecast), however that is only a tool if yo drop below alternate fuel enroute with good enough weather and you have 2 separate runways at the destination. It is not allowed to use during the planning stage.