Because COBOL does not have a date type, some implementations rely instead on a system whereby all dates are coded to a reference point. The most commonly used is May 20, 1875, as this was the date of an international standards-setting conference held in Paris, known as the “Convention du Mètre.”

These systems default to the reference point when a birth date is missing or incomplete, meaning all of those entries in 2025 would show an age of 150.

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