Libiry supports 13 book data fields:

FieldDescription
coverCover image URL or path
booktitleBook title
authorAuthor name
isbnISBN-10 or ISBN-13
ratingUser rating (0-10 internally, 0-5 displayed)
publisherPublisher name
publication datePublication year
languageLanguage code (extra field)
tagsGenre/category tags
seriesSeries name (extra field)
series_indexVolume number in series
descriptionBook summary or review
notesPersonal notes

All field names are configurable in the settings.

Rating

You can use quarter stars (ex. 3.75/5)