Represents flags for RDB$FIELDS system table.

    Bit
    Position   Description

    0          A SQL CHECK constraint is defined on this domain.
    1          AUTOMATIC set on insert.
    2          AUTOMATIC set on update.
    3          If check constraint fails, use name in message.
    4          Column is computed an IDENTITY sequence.
    5          View column is based on a read-only, or dbkey column.