access map as smtpd_sender_restrictions value

[Fabio Sangiovanni]

Hi list,

I've noticed that the syntax:
smtpd_sender_restrictions = pcre:/etc/postfix/sender_access

is valid, and by all means as effective as:

smtpd_sender_restrictions = check_sender_access 
pcre:/etc/postfix/sender_access

I couldn't find this syntax in the documentation, would you please point 
me to the right direction?

Thanks,
Fabio Sangiovanni