If only the argument sos is provided and the flag empty is set to TRUE or FALSE, this function returns a character vector with the site ids.
If listPhenomena = TRUE, the data.frame contains the column containing the site ids and a character column phenomenon where sites with several phenomena are repeated for each of their phenomenon.
If includeTemporalBBox = TRUE, the data.frame also contains two character columns beginTime and endTime indicating per site id and phenomenon its earliest and latest observation time point.