You don’t always want every record. A range lets you export just the ones you choose – exactly the way InDesign lets you pick pages.
Enter a range the same way you would in InDesign: individual numbers and spans, separated by commas. For example, 1-10, 15, 20, 21 exports records 1 through 10, plus 15, 20, and 21 – everything else is skipped.
Combine your output into a single book: What Is a Book File?