The RDB$PRIVILEGES system table describes the protection for
    the database objects. There is one row per grantor, grantee, and
    privileges combination per entity in the database.

    A row is stored in the RDB$PRIVILEGES table for each user who
    grants another user privileges for a database object.

    If the privilege for a database object was granted without the
    SQL GRANT option, the row of the grantor and grantee is modified.

    The privilege change takes effect at commit time of the command.

                                   NOTE

       The RDB$PRIVILEGES system table is used only in ANSI
       databases.

    The following table provides information on the columns of the
    RDB$PRIVILEGES system table.

                                Data
    Column Name                 Type      Summary Description

    RDB$SUBOBJECT_ID            integer   The id of the column
                                          or routine for which
                                          protection is defined.
                                          If protection is on a
                                          database, module, table,
                                          or view, this field is
                                          NULL. The value stored in
                                          this column must be unique
                                          within the database.
    RDB$OBJECT_ID               integer   The id of the module,
                                          table, sequence, or view
                                          for which protection is
                                          defined. The column is
                                          NULL if the protection is
                                          defined for the database.
                                          The value stored in this
                                          column must be unique
                                          within the database.
    RDB$GRANTOR                 integer   The binary format UIC of
                                          the person who defined or
                                          changed the privileges.
                                          This is usually the UIC of
                                          the person who executed the
                                          protection command.

                                          For an SQL IMPORT
                                          statement, the UIC is
                                          that of the person who
                                          originally defined the
                                          protection for the user;
                                          not necessarily the person
                                          who performed the SQL
                                          IMPORT statement.
    RDB$GRANTEE                 list      The binary format of the
                                of byte   UICs of the persons who
                                varying   hold privileges on the
                                          database object.
    RDB$PRIV_GRANT              integer   Specifies the access mask
                                          of privileges that the
                                          grantee has that he can
                                          grant to other users.
    RDB$PRIV_NOGRANT            integer   Specifies the access mask
                                          of privileges that the
                                          grantee has that he can use
                                          himself but cannot give to
                                          other users.
    RDB$FLAGS                   integer   Flags.
    RDB$SECURITY_CLASS          char(20)  Reserved for future use.