An international standards body has approved creation of a merchant code for gun retailers, a representative said on Friday, following pressure from activists who say it will help track suspicious weapons purchases.

At a meeting this week, a subcommittee of the International Organization for Standardization approved what is known as a “merchant category code” for firearms stores, a spokeswoman said.

The decision by the Geneva-based nonprofit was long sought by advocates of tighter gun regulation, such as US Senator Elizabeth Warren and other Democrats including New York City Mayor Eric Adams.

It clears the way for banks that process gun retailers’ payments to decide whether to assign the new code to merchants. The code would help monitors track where an individual spends money, but would not show what specific items were purchased.

The codes were requested of the Swiss body known as ISO by Amalgamated Bank of New York, which calls itself a socially responsible lender and investor.

In a statement, Amalgamated Chief Executive Priscilla Sims Brown said the codes will allow financial institutions to use new tools to detect and report suspicious activity associated with gun trafficking and mass shootings, without impeding legal gun sales.

“This action answers the call of millions of Americans who want safety from gun violence,” Brown said.

Some gun-rights activists had worried the new codes could lead to unauthorized surveillance.

Mass shootings this year including at a Texas elementary school that killed 19 children and two teachers have added to the long-running US debate over gun control.

Several top US pension funds had submitted shareholder resolutions asking payments companies to weigh in on the issue.

After the ISO decision was first reported by Reuters on Friday, a number of gun-control activists and politicians called for payment companies to adopt the new codes. Several cited news accounts of how mass shooters had bought high-powered guns on credit.

New York State Attorney General Letitia James wrote on Twitter that “credit card companies must now take the next step and flag suspicious transactions on gun and ammunition sales like they do for fraud and money laundering.”

A representative for Mastercard

(MA) said that following ISO’s approval, “We now turn our focus to how it will be implemented by merchants and their banks as we continue to support lawful purchases on our network while protecting the privacy and decisions of individual cardholders.”

American Express

(AXP), in a statement sent by a representative, said when ISO develops a new code the company works with third-party processors and partners on implementation.

“We are focused on ensuring that we have the right controls in place to meet our regulatory and fiduciary responsibilities, as well as prevent illegal activity on our network,” the company said.

Representatives for Visa

(V) did not respond to questions.