Wikipedia
In art history, a notname is an invented name given to an artist whose identity has been lost. The practice arose from the need to give such artists and their typically untitled, or generically titled works, an acceptable if unsatisfactory grouping, avoiding confusion when cataloging. The word derives from the German Notnamen, which has no real equivalent in English; the phrases names of convenience and emergency names (other awkward translations) are sometimes used to describe anonymous masters; nonce name was at one time used, but fell from favour as the word nonce took on different connotations.
The practice of giving generic names to unidentified artists is most common in the study of art of the antiquity especially of the Roman era, or with artists of the Northern Renaissance until about 1430. Typically a pseudonym is applied after commonality is established for a grouping of works, of which a similarity of theme, style, iconography, biblical source or physical location can probably be attributed to one individual or workshop, but because of lack of surviving documentary record, the name of that individual is lost. Groupings of works under a given notname can often be contentious; in specific cases art historians have argued that the reality may be a group or school of artists working under a common influence or commercial demand. Linking a generically titled old master with a historical person is usually a tempting and exciting prospect, and would establish an art historian's reputation.
The given notname usually depends on the artist's location, the most distinctive feature of their work, or the theme or iconographic element they are best associated with. Some notnames created based on a single artwork, called namepiece. Well known examples include the Master of the Embroidered Foliage (active c. 1480 to c. 1510) so named after his distinctive way of painting grass and trees, the Master of the Life of the Virgin (active c. 1463 to c. 1490) and the Master of the Legend of the Magdalen (active c. 1483 – c. 1527) both named after scenes from the Life of the Virgin attributed to them, the Master of the Prado Adoration of the Magi (active c. 1475 – 1500) named after his most famous panel, and the Vienna Master of Mary of Burgundy (c 1470 – c 1480), named after a manuscript owned by one of his patrons. The Berlin Painter (active c. 490s-c. 460s BCE) was named by Sir John Beazley for a large lidded amphora in the Antikensammlung Berlin, the Berlin Painter's namepiece.
In the case of 14th and early 15th-century Netherlandish, French and German painters and illuminators, the problem is particularly acute and stems from a number of factors. Primarily, the practice of signing and dating works is rarely seen in the region until the 1420s, and the inventories of collectors were uninterested in the artist's names. Many of the unidentified late 14th and early 15th-century northern artists were of the first rank, but because they have not been attached to any historical person, have suffered from academic neglect. It is probably a truism to say that, as Susie Nash put it, "much of what cannot be firmly attributed remains less studied". Some art historians believe that this has led to a lack of caution in connecting works with historical persons, and that such establishments often hangs on thin threads of circumstantial evidence. The identities of a number of well known artists have been founded on the basis of a single signed, documented or otherwise attributed work, with similar works sharing close style or within a geographical range also attached to that name. Examples include Hugo van der Goes, Campin, Stefan Lochner and Simon Marmion.