A file exists for each letter of the alphabet, all numbers, and a period. That means that each file is the starting point for all word searches by matching the first letter of the word.
Once a browser has a data file in local storage, it no longer needs to retrieve the file.
When the database files are replaced, a new time stamp is added. This time stamp tells the browser whether or not a new data file needs to be stored.
There is one other file, it contains what will be shown with each result (title and description).