I think they used LaTeX internally, but I've no way to be sure. They provide latex style sheets and sample files, and so those were my starting point. Of cours

I think they used LaTeX internally, but I've no way to be sure. They provide latex style sheets and sample files, and so those were my starting point. Of course, they are a big organization, and latex is a simple system, so they might have a program that translates it to something else, e.g. using latex to create PDFs and something else for other formats. But at least at the galley-approval stage, it was still LaTeX.