level 1: all core Debian Installer packages;. This level is splitted in five "sublevels" by order of strings priority (sublevel 1 groups together the strings used in all default installs while sublevel 5 groups together very rare strings used only for uncommon architectures).

level 2: all non core Debian Installer material involved for user interaction screens during a default priority installation of a Debian base system with default choices;

level 3: all material indirectly related to installation;