• Drawings that are produced as a result of training under the tutelage of a master or an institution.

Use for: Testing

• Documents containing affirmation of person's character or the value of a thing. Specifically, written declarations stating an individual's achievements or the usefulness of a product or service, such as a letter of endorsement.

Use for: Ferrotypes (prints)

• Photographs produced by the wet collodion process directly on lacquered metal, usually iron.