A summary of, or a commentary about, the reference.
Keywords
When defining keywords, it’s a good practice to imagine what you will be likely to search for when you want to retrieve the reference months or years later. Using the Keywords List (and Insert button) or the Peek function will ensure conformity. The searches in Bookends ignore capitalization.
Notes
For comments and observations. When importing references with the built-in importers (Medline/Medlars, Dialog, BRS, etc.), you can choose to place any information following an unknown tag in this field.
Data Validation
You can choose to have Bookends check each author, keyword, editor, and/or journal entry against the existing Lists or the Journal Glossary. If the new entry is not in appropriate list, you will be notified and can take one of several actions.
In Preferences you can elect to ‘validate’ authors, keywords, editors, and/or journal entries:
 
(Note that for author and keyword validation to be turned on, you must also have checked ‘Save Lists between launches’.)