[Note: Büton Rinchendrup was the great fourteenth-century scholar of Shalu monastery in west-central Tibet and oversaw or influenced much of the book-making at the time. In this quote, he's thought to be writing to the editors engaged in copying the Tengyur, part of the Tibetan Buddhist cannon.]
Büton advises the editors that "Since an understanding of the word and the meaning are dependent upon one another, when some doubt arises, understand the meaning from the word by looking at [the word] analytically, and the [correct] graph will be understood from the meaning." In other words, the text should make sense, and if it does not the editor is encouraged to emend it in accordance with his reasoned understanding of what the text should say. The act of editing was for Büton an act of personal interpretation, at least in part. This method no doubt led to many problems, and not a few anonymous editors have been accused of fabricating meanings in their efforts at conjectural emendation. Indeed, one of the most serious charges against authors and editors alike is that the texts they produce are self-made (rang bzo) and therefore not in accordance with tradition. Büton's positive assessment of conjectural emendation constitutes a significant difference between him and many later editors, who considered it to be a major source of textural error.
I was surprised to learn that the exact replication of the Buddhist cannon was rare throughout the 14-18th centuries and that changing the text was acceptable to one degree or another. That's very different than the exact, careful replication--down to the smallest mark--by the Israelite scribes copying the Hebrew scriptures!