[oshirisuki]

I think it's the same as ms-office, they make a format, and they are the only ones that make the software to use the files in that format, it's funny, because adobe reader is very bad, and they ended up "giving it up", now ISO handles the spec, as for generating PDFs, maybe check libreoffice? or some other software that creates PDFs with the source available

[alexaholic]

MS Office switched to XML tentatively in 2003 and fully in 2007. The latter formats were standardized (Ecma, ISO) into Office Open XML, but even the previous version were accessible. I don’t remember whether the spec was publicly available, but you could study the output of some valid documents and figure out what went where.