This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Egon Wellesz's study of Byzantine music and hymnography shows how much of what scholars know about an older chant tradition depends on reconstructing a notation system that had already gone out of common understanding by the time serious study of it began. Byzantine neumes recorded pitch and ornament in a shorthand meant for singers who already knew the melodies by ear, so a modern scholar reading the same signs has to reconstruct, rather than simply read, exactly what an early cantor sang.
That reconstruction work matters for how a sacred sound entry is written, since two traditions can look similar on the page, a repeated melodic formula, a marked pause, a symbol for ornament, while meaning something different in practice, and a scholar who has not learned to read a specific tradition's own notation risks importing assumptions from a better documented chant tradition studied earlier.
The same caution applies well beyond Byzantine chant. Wherever a sacred sound entry describes a tradition's own system for preserving and transmitting a sung or chanted practice, whether through written notation, a fixed oral curriculum, or both together, the entry tries to describe that transmission method on the tradition's own terms, since how a chant was actually taught and passed down is itself part of its documented history.