Yong-le: Year 6, Month 9, Day 1
20 Sep 1408
The Ministry of Rites noted that the ceremony and ritual for the audience of the king of the country of Bo-ni with the Heir Apparent had not yet been fixed. The Emperor said: "The king of the country of Bo-ni is a feudatory minister. Use the ritual applicable for Dukes, Marquis and senior ministers when they have an audience with the Heir Apparent."
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 11, page 1109