Is set if: 64 more optional information bits are present.
Effect if set:
After the 16-bit field, to determine the existing optional information, follows one additional 64-bit field for the determination more optional information. These bits are for future uses and are currently not used.
If not set: The 64 more optional information bits are not present.
Effect if not set:
After the 16-bit field no more bits follow for additional optional information.