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. They should be listed as absolute pathnames, and should exist in the binary package, otherwise dpkg(1) will ignore them (although by default dpkg-deb(1) will refuse to build such binary packages). 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