But several people familiar with the negotiations told us that there are likely to be certain elements of the complicated agreement to relax sanctions in exchange for inspections of Iran’s nuclear infrastructure that would have to be kept from public view. For example, the precise details of how the International Atomic Energy Agency will inspect and monitor Iranian facilities is likely to be secret because the agency doesn’t want to tip off other proliferators. The names of Iranian scientists associated with the program whom the agency would like to interview will also not be shared with the public.

There is also a potential for difficult gaps between the Western and Iranian positions to be papered over with mutual, but secret, interpretations of vague text in the agreement. Iran’s supreme leader, Ayatollah Ali Khamenei, has publicly said that no military facilities should be inspected, whereas Western leaders have insisted there would have to be such monitoring. An undisclosed interpretation could be a way to bridge this kind of gap and allow both sides to save face.