Property :: relativePosition - Get relative position of current or last instance
The function returns the relative position of the currently or last selected instance. This may differ from the absolute (current) position in case of filter conditions or selection by context handlers.
When no instance has been selected or when no relative position is known for the instance currently selected (e.g. when being selected by key), the function returns -1 . When passing bLast= true , the function returns the last relative index registered for the property handle.
The relative index is updated only, when calling getRelative() function for accessing the collection.
When an error has been detected, the function throws an exception.
The position of an element in a collection is beginning with 0 for the first element.