Docbook is a markup format in either XML or SGML which was designed in part by O'Reilly for the publication of their books (although I do not believe it has bee

Docbook is a markup format in either XML or SGML which was designed in part by O'Reilly for the publication of their books (although I do not believe it has been used for this purpose for many years). The XMl variant is far more popular today, but that's not saying a lot as Docbook itself has become rather obscure. It doesn't really take on the problem of equations but does handle structured documents in a way which is much more flexible and arguably powerful than LaTeX, since you can use the full power of XML tooling including e.g. XSLT to define document components. That said, I think it's quite simply too verbose to be popular, not to mention the tooling around it tends towards archaic. I had a friend who was an extremely heavy Docbook user but had configured his emacs to insert most tags by key-chord, making it much more efficient to write. It's very hard to deal with if you don't do that.