DIN stands for “Deutsches Institut für Normung“, meaning “German institute for standardisation”.
DIN standards are still valid for products having no ISO or EN standards.
The (ASTM) American Society for Testing and Materials has developed different standard & speficiation for Bolt fasteners for variety of uses.
Japanese Industrial Standards specifies the standards used for industrial activities in Japan. The standardization process is coordinated by the Japanese Industrial Standards Committee and published through the Japanese Standards Association.
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.
GB standards are the Chinese national standards issued by the Standardization Administration of China, the Chinese National Committee of the ISO and IEC. Mandatory standards are prefixed “GB”.