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, flora, fauna, weather.
Orange links (Literature) signal allusions to published texts, whether of poetry, fiction, drama, essays, criticism and aesthetics, history, philosophy, scripture, theology, travelogues, 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 cultural ephemera such as newspapers and money.
Purple links (Performances) indicate notes about songs, stage plays, nursery rhymes, speeches, recitations, advertising pitches, liturgical rites, calculated social acts, 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, his styles, effects, techniques, revisions, aesthetic theories, and artistic development, and questions of how well different printed texts may reflect his intentions.
These categories are arbitrary, and often the decision to assign a note to one of them must be arbitrary too, since several notes don't fit any category neatly and many 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.