docs: def _addSortParam(self, field, order=''):
  		"""Adds a sort parameter, order have to be in ['ascend', 'ascending','descend', 'descending','custom']"""
  
  		if order != '':
  			validSortOrders = {
  				'ascend':'ascend',
  				'ascending':'ascend',
  				'<':'ascend',
  				'descend':'descend',
  				'descending':'descend',
  				'>':'descend'
  			}
  
  			if not string.lower(order) in validSortOrders.keys():
  				raise FMError, 'Invalid sort order for "' + field + '"'
  
  		self._sortParams.append(
  			[field, validSortOrders[string.lower(order)]]
  		)