Editing Assignment (law) (section)

===Revocability===
Assignments made for consideration are irrevocable, meaning that the assignor permanently gives up the legal right to take back the assignment once it has been made. Donative assignments, on the other hand, are generally revocable, either by the assignor giving notice to the assignee, taking performance directly from the obligor, or making a subsequent assignment of the same right to another. There are some exceptions to the revocability of a donative assignment:
#The assignment can not be revoked if the obligor has already performed
#The assignment can not be revoked if the assignee has received a ''token chose'' (''chose'' being derived from the [[French language|French]] word for "thing", as in a chose of action) - a physical object that signifies a right to collect, such as a stock certificate or the passbook to a savings account.
#The assignment can not be revoked if the assignor has set forth in writing the assignment of a ''simple chose'' - a contract right embodied in any form of token.
#[[Estoppel]] can prevent the revocation of a donative assignment if the assignee changed their position in reliance on the assignment.