Current behavior: When a player signs up for an event, they have the option in a little box to the right of the character box to give a comment. Alternatively, from the client, event/signup <#>=<comment> can be used. Often this is used for availability caveats or willingness to be a backup on a crowded event. However, when canceling a signup, there is simply a cancel button or event/cancel <#>.
Suggestion: Add a similar comment box/=<comment> function for canceling. This would allow players to tell the GM why they are canceling directly via the event.
Rationale: While players can certainly page or mail this information to the GM, having a box/command baked into the action of canceling the signup increases the likelihood that this will actually happen. Mushers are human beings and having more communication helps prevent hurt feelings and burnout for people running events.