This duplication violates the principle of a . When one copy is updated and another is not, data corruption occurs. Worse, when an employee leaves, their local ids.xls remains on their laptop—an easy target for theft.

If the answer is no, you have just found your next security or compliance project.

The spreadsheet opened up like a ledger from another life. Columns of numbers marched under terse headers: ID, Source, Timestamp, Status. Most rows were mundane—serials, timestamps, simple flags—but a handful were different. One row had an ID that matched the number on the faded business card he'd kept in his wallet for ten years. Another row carried a timestamp that coincided with a night he could not fully remember but never forgot.

: Developers use these files to map old "legacy" IDs to new system IDs during software transitions.