Late Southern Sòng minor literatus and calligraphic prosopographer; zì Liángshǐ 良史, self-styled Xiánzhōng lǎosǒu 閒中老叟 (Old Man from the Idle Middle). Of unknown clan-seat and never holding office. Compiled the KR3h0035 Shūlù 書錄 in Chúnyòu rényín (1242) — a three-juàn prosopography of Sòng calligraphers (the imperial line, 110 Northern Sòng masters, 45 Southern Sòng masters, plus six women in an appended wàipiān). The original was destroyed by fire in Jǐngdìng 1 (1260); Dǒng reconstituted the work from a Cáo-family copy in Xiánchún 1 (1265). The book survived into the Yuán through a Zhìzhèng 27 (1367) Huátíng 華亭 Sūn-family hand-copy. CBDB has no firm record matching this Dǒng Gēng.