deb-conffiles man page
deb-conffiles — package conffiles
A package declares its list of conffiles by including a conffiles file in its control archive (i.e. DEBIAN/conffiles during package creation).
This file contains a list of files, one per line. Trailing whitespace will be trimmed, and empty lines will be ignored.
/etc/alternatives/README /etc/cron.daily/dpkg /etc/dpkg/dpkg.cfg /etc/logrotate.d/dpkg