original-public-domain
2 claims in this dataset rest on this source.
The rule of the Byzantine office in its printed recensions. It marks every day of the Menaion with one of six signs — a cross in a circle for a Great Feast, a cross over a semicircle for a vigil, a plain cross for polyeleos, then the doxology and six-stichera marks, then no mark at all — which is the nearest thing any tradition has to a machine-readable rank, and is what the stars on this site are mapped from.