The conventional way of describing the relation between the artist and the work of art that is presented. Examples:
Monet. The Auctionist Experts believe this is an original work by the artist.
Monet. Replica. The Auctionist Experts believe that the artist him/herself made this work as a replica of their own, previous original.
Monet. Attributed to. The Auctionist Experts find it likely that this is an original work, but is not prepared to guarantee this.
Pablo Picasso. His studio. The Auctionist Experts believe that the work was made in the artist's studio and possibly under their supervision.
Pablo Picasso. His circle. The Auctionist Experts thinks that the work was made by another artist but during the lifetime of the named artist and in their manner.
Pablo Picasso. Follower of. The Auctionist Experts thinks that the work was done in the manner of the named artist, during their lifetime or later.
Pablo Picasso. In the manner of. The Auctionist Experts thinks that the work is done in the manner of the named artist but after their lifetime.
Pablo Picasso. After. The Auctionist Experts believe that the work was made by another artist, based on an original work by the named artist.