String freezes are special periods in the Debian Installer development process. They are more detailed in Section 1.7, “ String freezes and the Debian Installer release process ”.
In short, during the release process of Debian Installer, the release manager will call for string freezes. A string freeze theoretically forbids any change to templates files in Debian Installer packages. It is meant for translators to complete their work without having it outdated by maintainers changes.
Of course, some urgent or critical changes may be needed even during a string freeze. Maintainers needing to commit such changes should first warn the Debian Installer release manager and the Debian Installer i18n coordinators and get their approval before committing.
The Debian Installer i18n coordinators will warn translators about the unplanned change and will request them for a special update.
Always remember that Debian Installer translation is the work of several dozens of teams and thus each change adds more time for all of them to get synchronized again.