Elaborate two-dimensional designs called "flat designs" are characteristic of Northwest Coast art and are tightly controlled by formal canons of both line and form. The Haida made far fewer large-scale paintings, such as housefronts and screens, than their Tsimshian neighbours. The Haida were, however, the masters of subtly sculpted flat design -- a kind of bas-relief -- in which the secondary and tertiary spaces were enhanced with gently swelling or concave planes between the primary formlines. In the past, the Haida used less complex textured zones of cross-hatching or parallel lines around eye forms than did Tsimshian and Heiltsuk artists. Although early Haida artists are not known by name, art historian Bill Holm, after a close study of disparate works such as totem poles, housefront paintings, chief's seats and argillite carvings, identified one early master painter and sculptor as "the Master of the Chicago Settee," after the first piece of his work to attract the appreciation of experts like Holm, Wilson Duff and Haida artist Bill Reid.