The mandatory sign is either a light blue circle with a white border or a white circle with a red border, it is not used in Australia, Ecuador, or the United States.
In Vienna Convention signatories, the mandatory sign is either a light blue circle with a white border (Type A) or a white circle with a red border (Type B). The mandatory sign group is not used in Australia, Ecuador, or the United States, none of which are signatories to the Vienna Convention. 
