Chant Notation
Chant is one of the first musics that notation has survived for. To see how inexact early chant notation is, note these early notations of the chant: Viri Galilaei. Here also the Brazilian monks' version.

Viri Galileai in an 11th Century Manuscript from Montpelier

Viri Galileai in chant notation

Viri Galileai in modern notation
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