| signiert | by the artist's own hand |
| bezeichnet | possibly by someone else's hand |
| zugeschrieben | is an allocation to the oeuvre of an artist because of the likeness in style and tradition, which is incapable of proof though |
| Werkstatt | works, which probably have been made in the studio, viz in immediate environment of the artist |
| Schule | works, which have been created stylistically and chronologically very close to the artist |
| Kreis | works, which have been created in the sphere of influence of the artist |
| Nachfolge | works, which have been created in the artist's style, though later |
| Sammlerstück | exposed object with the highest quality grade of each auction category |
