For those who do not follow the development of procedures at LSZS closely: The IFR procedures are permanent since a few month, meaning that a pilot can fly IFR to/from LSZS. ATC is only provided for the part of the flight with Swiss Radar, FL160+. Below only FIS is offered, with Swiss Radar or Samedan Info.
There is an approach to both runways (03: VISUAL APCH WITH RNP GUIDANCE, 21: RNP), the minimas are therefore quite different. The departures from both runways are similar, be aware of the equipment requirement for the different types.
What does this mean? A pilot performing an IFR departure will receive a departure clearance on the ground (SID, squawk, etc.) and is then allowed to enter controlled airspace according to the SID. There is still no take off clearance given, what can be used is a time limit for departure due to arrivals (as you probably know from the US). Or a pilot departs VFR and will need an IFR clearance (joining) once airborne.
Arrivals either cancel IFR or fly the procedure (similar to LSGS), without landing clearance.
Good practice is therefore to request the intentions of a arrival (if nothing is filed in the flight plan) or inform those on ground about the possibilities, as from experience not all pilots will contact Swiss Radar for an IFR departure. But as everybody is reading this post...