property Address: string;

Address is a read-only String property that contains the string representation of the 128-bit IPv6 address for the resource record type. 

Values in Address are in network byte order (high-order byte first), as described in the Internet Standards document: 

RFC 1884 - IP Version 6 Addressing Architecture  

Values in Address are assigned when Parse is called using the raw byte values for the resource record in TQueryResult.Add.