code: def get_coordinate_system(self):
          
          coordinate_list = ['specimen']
          initial_coordinate = 'specimen'
          for specimen in self.specimens:
              if 'geographic' not in coordinate_list and self.Data[specimen]['zijdblock_geo']:
                  coordinate_list.append('geographic')
                  initial_coordinate = 'geographic'
              if 'tilt-corrected' not in coordinate_list and self.Data[specimen]['zijdblock_tilt']:
                  coordinate_list.append('tilt-corrected')
          return initial_coordinate, coordinate_list
docs: Check self.Data for available coordinate systems.
  
          Returns
          ---------
          initial_coordinate, coordinate_list : str, list
          i.e., 'geographic', ['specimen', 'geographic']