48 Across
NYT Daily • August 30, 2025
Library catalog ID
Answer:
ISBN
Hint:
Not available
Explanation:
A library catalog ID often refers to a unique identifier for books, and the most common one is the ISBN, or International Standard Book Number. It’s a numeric code that helps libraries and bookstores track and organize titles. The clue is straightforward—no wordplay—just pointing to the standard system used worldwide for book identification. Think of it like a book’s fingerprint.