I don't think this is a bad idea per se, but it seems to me that comparing it to Markdown is a poor way of communicating the intent and utility of this markup language. Markdown's central design principle is that, by adopting semantic markup conventions from email, it is readable in plain-text form even to someone who hasn't set out to learn the conventions. That severely limits the kind of thing you can express in Markdown, but that's an acceptable (even desired) tradeoff in the majority of situations where Markdown would be useful in the first place.
Because Markdown doesn't cover everything, and because there are other sets of semantic markup conventions used in a plain text setting, there's certainly room for "Markdown-likes" which attempt to replicate the same kind of effort with those other conventions in mind. For example, Fountain[1] is a language for writing screenplays, and its conventions are a fairly close (though not as close as possible) approximation of the same ones used in real screenplays.
I've never authored a manuscript for a book, so I don't know myself whether such conventions for things like tables of contents exist in the publishing world. But I have a feeling that if they do, they wouldn't look like this. What UBook actually reminds me of is troff/nroff macro syntax[2], which was developed for a similar purpose and is still in use today as the lingua franca of Unix manpages.
You've implied in other comment threads that you don't really intend this for writers to use directly. If this were to be the output of a more user-friendly writing tool, I'm curious what such a tool might look like, and how it could differ from existing WYSIWYG rich text editors (where everything looks like a nail and your hammers are labeled "bold" and "bigger font"). For example, how would you represent section and paragraph structure in an editable way without the use of inline control characters that you edit the same way as other text? I don't think I've ever seen an editor built that way, but if that's what you're going for, I look forward to it.
Because Markdown doesn't cover everything, and because there are other sets of semantic markup conventions used in a plain text setting, there's certainly room for "Markdown-likes" which attempt to replicate the same kind of effort with those other conventions in mind. For example, Fountain[1] is a language for writing screenplays, and its conventions are a fairly close (though not as close as possible) approximation of the same ones used in real screenplays.
I've never authored a manuscript for a book, so I don't know myself whether such conventions for things like tables of contents exist in the publishing world. But I have a feeling that if they do, they wouldn't look like this. What UBook actually reminds me of is troff/nroff macro syntax[2], which was developed for a similar purpose and is still in use today as the lingua franca of Unix manpages.
You've implied in other comment threads that you don't really intend this for writers to use directly. If this were to be the output of a more user-friendly writing tool, I'm curious what such a tool might look like, and how it could differ from existing WYSIWYG rich text editors (where everything looks like a nail and your hammers are labeled "bold" and "bigger font"). For example, how would you represent section and paragraph structure in an editable way without the use of inline control characters that you edit the same way as other text? I don't think I've ever seen an editor built that way, but if that's what you're going for, I look forward to it.
[1]: http://fountain.io/
[2]: http://liw.fi/manpages/