Sūn Yán 孫炎, zì Shūrán 叔然, a Three Kingdoms (Sānguó) period philologist conventionally credited with the invention of fǎn qiè 反切 — the system of indicating Chinese pronunciation by combining the initial of one character with the final of another. The dating of fǎn qiè to Sūn Yán’s time is cited in the Sìkù notice on KR1a0133 as grounds for rejecting 李光地 Lǐ Guāngdì’s claim that pre-imperial canonical text could contain fǎn qiè notation.