Emperor Taiwu of Northern Wei
The custom of naming taboo had a built-in contradiction: without knowing what the emperors' names were, one could hardly be expected to avoid them, thus somehow the emperors' names had to be informally transmitted to the populace to allow them to take cognizance of and thus avoid using said characters. In one famous incident in 435, during the Northern Wei Dynasty, Goguryeo ambassadors made a formal request that the imperial government issue them a document containing the emperors' names so that they could avoid offending the emperor while submitting their king's petition. Emperor Taiwu of Northern Wei agreed and issued them such a document. However, the mechanism of how the regular populace would be able to learn the emperors' names remained generally unclear throughout Chinese history.