Default:0
>= 0<= 499
Specifies which field to use for sorting. Allowed fields are
publicName.dutch, publicName.english, iata, country and city… Use plus
or minus sign to indicate ascending or descending order.
Match pattern:^((\+|-| )?(publicName\.dutch|publicName\.english|iata|country|city)(,|$))+$
Default:+iata
<= 25 characters