Rubric

In these, red letters were used to highlight initial capitals (particularly of psalms), section headings and names of religious significance, a practice known as rubrication, which was a separate stage in the production of a manuscript.

[4] Instructions for a priest explaining what he must do during a liturgy were also rubricated in missals and the other liturgical books, and the texts to be spoken aloud were in black.

Red is also often used to distinguish words spoken by the celebrant and those by the congregation, or by other specific persons involved in the liturgy, e.g., those marrying.

[7][8] Around 1900, rubrication was incorporated into a red letter edition of the King James Version of the Bible to distinguish the Dominical words, i.e., those spoken by Jesus Christ during his corporeal life on Earth, because that translation lacked quotation marks.

A rubric is an explicit set of criteria used for assessing a particular type of work or performance and provides more details than a single grade or mark.