//Virtual Plane - you will need to add another property, like
//PropertyString IndependentVariable t
//PropertyString IndependentVariable z
//That defines the indepenent variable used in integration
//If IndependentVariable is t, you will also have to add
//PropertyDouble PlaneTime <some_time>
//Particles will be output at times corresponding to the double value of <some_time>
//Else the z position will be used

Module Virtual
{
  Volume     None
  PropertyString SensitiveDetector   Virtual
}