passdb evaluation order

Hello,

I could have several password databases in dovecot. And according to 

http://wiki.dovecot.org/PasswordDatabase these passwdbs could allow or deny users and they could have different result_failure and result_sucess behaviors. So the order in which they are evaluated may be significant.

So, how do I define this order?

-- Angel L. Mateo Martínez Sección de Telemática Área de Tecnologías de la Información y las Comunicaciones Aplicadas (ATICA) http://www.um.es/atica Tfo: 868889150 Fax: 868888337