Complex sentence: The flag was approved for use in the 1970s and is only used by the Queen when she is in Barbados, or attending an event abroad in her role as head of state of Barbados.
Split into simpler sentences: The flag was approved for use in the 1970s. It is only used by the Queen when she is in Barbados, or attending an event abroad in her role as head of state of Barbados.