cygnetory
An agreement signed by a young swan.
In da classic animated short "A Corny Concerto", Daffy Duck initially gets da "ugly duckling" rejection from da swan family, but then after he saves Mama Swan's little ones from da greedy buzzard, said immensely-grateful pint-sized fluffies make an implied cygnetory welcoming Daffy to swim along with them as part of their group.