Colour-Notes, In A Collection Of St. Jerome's Letters
The writings of St. Jerome (c.340-420) are numerous and voluminous, and include works on the Bible, theological controversies, histories, translations (notably a new translation of the Bible into Latin), and letters. This manuscript contains a collection of the 120-odd surviving letters (some of them written to Jerome, rather than by him), many of them originally composed with a view to publication. The final page has a medieval ownership inscription of Chertsey Abbey, in Surrey.
Colour-notes are small indications--usually letters of the alphabet--provided during the making of a manuscript, to help the artist of the initials observe correct alternation of the colours used. On this page, for example, about half-way into the left margin next to the two coloured initials, one can see the small letters 'G'(reen) and 'R'(ed).