Except in the first few Wars, fans intending to participate are required to send permission slips to the listowners in which they agree to be used as characters, whether in their own or other people's war posts. As a result, there is a ritual call for permission slips shortly after the date is officially set for a new war. No one who has not submitted a slip is allowed to participate; nor are writers allowed to write fans into their stories unless a slip is on file for them.