a second confirming signature endorsing a document already signed
Countersigning means writing a second signature onto a document. For example, a contract or other official document signed by the representative of a company may be countersigned by his supervisor to verify the authority of the representative. ...
A signature made to confirm or endorse another
The signature of a licensed agent or representative on a policy that is required to validate the policy
An authorized signature of agent or company representative on an insurance policy. Usually pertains to policies sold by an agent of the insurer located in another state.
Signature of someone other than the artist that adds either additional authenticity or historical value to a limited-edition print.