In the "Tang Yun" (Tang Rhymes), the pronunciation is noted as shi lin qie, with the same pronunciation as "chen". "Shuowen Jiezi" (Explaining Characters and Analyzing Words) explains it as: the time when the sky is about to brighten in the early morning. The character is composed of "cong" and "chen". "Chen" represents the hour of chen. For a detailed explanation, please refer to the notes for the character "chen".