[3] Du Taiqing (t 杜臺卿, s 杜台卿, Dù Táiqīng, w Tu T‘ai-ch‘ing; born c. 536) drew from Zong's work in composing his own seasonal calendar, the Precious Canon of the Jade Candle (t 《玉燭寶典》, s 《玉烛宝典》, Yùzhú Bǎodiǎn, w Yü-chu Pao-tien), shortly after 581.
[14] His nephew Du Gongzhan (杜公瞻, Dù Gōngzhān, w Tu Kung-chan; died after 590)[14] used the Precious Canon to revise and annotate Zong's text sometime in the late Sui or early Tang.
[4] The Suishiji is an annotated record of its major festivals in the mid-6th to early 7th century,[3] during the chaos of Sui's creation and collapse and just before the stability and grandeur of the Tang.
[6] The work also includes irregularly observed rituals and celebrations concerning disease, bodily functions, marriage, childbirth, dancing, and the exorcism of evil spirits.
Zong quoted the apocryphal Yulanpen Sutra and described the holiday during his time: people offered temples flowers, flags, and bowls and joined monks and nuns in drumming and singing.
[2] Du's commentary on Zong's section about the Cold Food Festival supports the idea that it derived from an old Zhou ritual about banning fire in the capital[19] during the last month of spring.