The new credit card code offers a "significant" new tool for identifying mass shooters, one advocate said.

A new "merchant code" for credit cards will categorize purchases made at gun stores. But there are limitations on its usefulness — including that most guns in the U.S. aren't bought at such outlets.

A credit card security code is a three- or four-digit number that’s found only on a physical credit card.

A new "merchant code" for credit cards will categorize purchases made at gun stores. But there are limitations on its usefulness — including that most guns in the U.S. aren't bought at such outlets.

A credit card security code provides protection against fraud in online and over-the-phone transactions.

Some predict that FFLs will experience a significant increase in cash payments this year due to a newly adopted merchant category code (MCC) for firearm and ammunition credit-card purchases.

A credit card categorization code that could improve the tracking of gun sales was approved by an international panel that sets standards for the payments industry, according to New York City ...

For some credit card purchases in Canada, a postal code is required as a security measure. If using a credit card in the U.S., you may need to use a ZIP code instead.

A new "merchant code" for credit cards will categorize purchases made at gun stores. But there are limitations on its usefulness — including that most guns in the U.S. aren't bought at such outlets.