The six colors of hyperlinks embedded in the text indicate different categories of notes:
Green links (Ireland) refer to Irish history, politics, battles, customs, language, humor, religion, mythology, economics, regions, cities, sites of interest, modes of transportation.
Orange links (Literature) signal allusions to published texts, whether of poetry, fiction, drama, history, philosophy, scripture, theology, science, biography, or hagiography.
Brown links (Dublin) point to landforms like the river and bay, the built environment such as streets, canals, buildings, bridges, trams, and statues, and ephemera such as weather, newspapers, and money.
Purple links (Performances) indicate notes about songs, stage plays, nursery rhymes, speeches, recitations, advertising pitches, liturgical rites, calculated social behaviors, and impromptu clowning.
Red links (The Body) encompass anatomy, sexuality, childbirth, eating and drinking, excretion, clothes and accessories, disease and death, medicines and poisons, the physiology of emotion, the vagaries of memory, mental illness, dreams.
Blue links (The Writer) speak to Joyce's transformations of lived experience into fiction, and his styles, effects, techniques, revisions, aesthetic theories, and artistic development.
These categories are arbitrary, and very often the decision to assign a note to one category or another must be arbitrary too, since many notes might easily be placed in two or three. The Sandycove tower, for instance, may be understood as a physical structure in the environs of Dublin, as a remnant of Ireland's military history, and as a symbol evoking narratives in Homeric and Shakespearean literature. In such cases, the category that describes the largest amount of the note’s content is used. Occasionally, a colored symbol (§,§,§,§,§,§) at the beginning of a paragraph signals a shift to a new kind of content in the middle of a note.