In the Event entry system once a family has committed at least one athlete, the button will change from “Attend/Decline" to “Edit Commitment”. This designates to the family that they have at least one athlete either committed to attend this event or they have declined to go.

For teams that multi commit their athletes to attend and require a “check out” instead of committing, the button will designate to the families that they are committed unless otherwise updated.

See Also
Setting an Account or Member User Defined Field.
How do I see Athletes that have declined to go to an event?
Why aren’t my athlete’s times showing?