The move by Visa, Mastercard and American Express follows an International Organization for Standardization decision to implement a similar code, which will make it easier for authorities to flag gun purchases. (The New York Times, Bloomberg)

Talking point: Gun control advocates have long clamoured for a credit card code specific to firearms stores, which they say could also be used to block gun purchases to problematic individuals. Credit card companies have been under similar pressure to account for their use on pornographic sites owned by MindGeek. In July, U.S. District Court Judge Cormac Carney wrote that Visa provided payment services to the Montreal-founded, Luxembourg-based company “with the alleged knowledge that there was a wealth of monetized child porn on MindGeek’s websites.”