As a postgis maintainer and other tools relying on postgresql, I need to define an interval for postgresql. This allows you to avoid errors like this one at https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=234813 I had proposed this patch in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=213038 but it was not followed. I propose this patch independently. A review is associated here https://reviews.freebsd.org/D18818 Once approved, I will modify my ports requiring intervals and update the documentation. Thank you.