Before calling this program, you should have installed any X fonts provided by your package into the appropriate location in the package build directory, and if you have fonts.alias or fonts.scale files, you should install them into the correct location under etc/X11/fonts in your package build directory.
Your package should depend on xfonts-utils so that the update-fonts-* commands are available. (This program adds that dependency to ${misc:Depends}.)
This program automatically generates the postinst and postrm commands needed to register X fonts. These commands are inserted into the maintainer scripts by dh_installdeb. See dh_installdeb(1) for an explanation of how this works.
See Debian policy, section 11.8.5. for details about doing fonts the Debian way.
This program is a part of debhelper.