In every case, the reporter and the source must come to an agreement about how the information will be used. In other words, Musk prefacing his comments with “off the record” doesn’t trigger a binding contract. As Mac said in one of his emails to Musk, “I didn’t agree for the conversation to be off the record, but appreciate the response.”

That’s the bare definition. In practice, there’s more nuance. Mac could have conceded to Musk’s wishes, if he and his editors decided that the contents of the emails—an apparent reversal of Musk’s earlier public remarks about Unsworth—weren’t newsworthy. But they did, and they had every right to do so. “I think people that understand how this works and how ‘off the record’ works understand how important this story is and why we published this story, and that we did everything in the right,” Mac told me over the phone.

Another publication may have determined the emails weren’t worth publishing. BuzzFeed’s judgment was certainly in the letter of journalistic law. Whether it was in the spirit of it is a different question with multiple answers, and good fodder for discussion of general editorial decision-making.

There are some cases in which reporters don’t have much choice about the terms. A presidential campaign may invite reporters on the trail for a conversation with the candidate and stipulate beforehand that the whole thing will be off the record. Reporters must decide whether to accept the conditions and attend, or miss out. Compared to reporter-source relationships, their hands are tied when it comes to negotiating. But the premise of “off the record” remains: An agreement is made.

Perhaps part of the confusion for some sources stems from where these agreements are being made, or not made, in the first place. When reporters engage in shoe-leather journalism—actually talking to people, with their voices—perhaps the risk of confusion is lower. Bob Woodward is still walking around and knocking on sources’ doors, but many reporters do their work through email, texts, LinkedIn messages, Twitter DMs, Snapchat—the list goes on. These settings have only recently become fair game for traditional reporting, but they remain rooted in their earlier, casual uses. These channels may seem more friendly, less confrontational, which can exacerbate the ambiguity over the meaning of “off the record.”

The fundamental rules of off-the-record scenarios are, for journalists, unimpeachable standards. Yet for news consumers, they can be confusing. The replies to Mac’s tweet about Musk’s critique of “journalistic credibility” offers a small snapshot into the murkiness of the phrase’s meaning among the general population. “Any reasonable person would agree this was off the record,” one user said, to which another responded, “Reasonable people should understand how ‘off the record’ actually works before trying to invoke it.”