Northern-Sòng polymath — paleographer, calligrapher, and jièhuà 界畫 master, zì Shùxiān 恕先, hào Guóbǎo 國寳, of Luòyáng. After serving the HòuZhōu as Zhāosǎn dàfū, Zōngzhèngchéng, and Guózǐ shūxué bóshì, he survived into the early Sòng but was repeatedly demoted for offenses against court etiquette and died in exile in 977. Two of his philological works survive in the Sìkù: the Hànjiǎn KR1j0026 in 3 juàn — the most influential medieval compendium of gǔwén archaic-script graphs, drawing on 71 explicitly listed pre-Sòng sources; and the Pèiguī KR1j0027 in 3 juàn — a treatise on the differentiation of graphically confusable characters organized by tonal pairings. As a painter he is best known for jièhuà (architectural perspective drawing); the Xuējìtú 雪霽圖 in the Taipei National Palace Museum is attributed to him. CBDB lifedates: died 977, in agreement with the Sòngshǐ biography (juàn 442) and the catalog meta.