《明史·志·卷四十二》
朔日、望日朝拜、下发诏书、焚香叩拜、进献奏表、外国朝贺上贡、朝见皇帝，便穿皮弁服。
朔望朝、降诏、降香、进表、外国朝贡、朝觐，则服皮弁。
On days of conjunction or opposition, the emperor would hold court to issue imperial edicts, burn incense and bow, accept memorials, and receive foreign envoys presenting tributes; such occasions called for wearing the Pi Guan (cap with flaps) attire.