In 16.0, the PUBLISH authority is replaced by the PUBLIC.db_publisher database option. You change the publisher by changing the database option.
In IQ versions earlier than 16.0, the database publisher was controlled by using the GRANT PUBLISH and REVOKE PUBLISH statements. You determine the current publisher by querying the CURRENT PUBLISHER special value. The GRANT PUBLISH and REVOKE PUBLISH syntax is still supported, but deprecated.
You can also still query the CURRENT PUBLISHER to determine the current publisher.
The SET ANY SYSTEM OPTION system privilege is required to set PUBLIC.db_publisher.