Xú Yòngchéng 徐用誠 (zì Yànchún 彥純, fl. late Yuán to early Míng), Yuán-to-early-Míng physician of Huìjī 會稽 (modern Shàoxīng, Zhèjiāng). A sīshū 私淑 (private-disciple, by reading) of 朱震亨 Zhū Zhènhēng’s Yīn-deficiency school. Author of the original Yī xué zhézhōng 醫學折衷 — a 17-category clinical treatise — which was later expanded by Liú Chún 劉純 into the Yùjī wēiyì 玉機微義 (KR3e0068, 50 juan, 50 categories). Yáng Shìqí’s preface to the work locates the school of Xú Yòngchéng and Liú Chún in the Northern Zhāng Yuánsù → Lǐ Gǎo → Wáng Hǎogǔ transmission and the Southern Zhū Zhènhēng line — a syncretic placement the SKQS editors note as inaccurate (Xú and Liú are clearly Dān-xī-school disciples, not heirs of the Yìshuǐ / PíWèi school).