They're abusing filetype ambiguity. One file can simultaneously be valid HTML, ZIP and PDF, opening correctly in readers for each file format. Mostly it is beca

They're abusing filetype ambiguity. One file can simultaneously be valid HTML, ZIP and PDF, opening correctly in readers for each file format. Mostly it is because of lax requirements on file headers and structuring of the data inside. I guess they found a way to make it produce something your terminal can process.