Question: I was curious to know are code related questions in scope for ebook stack? Such as `.ncx` file issues, `.opf structure from ePub 3.0 VS ePub 2.0, how to extend validation frameworks, etc, etc.

Answer: 
For the immediate future we are being more accommodating so we can see what questions are coming in. When we have enough of a sample size we can better decide what will be in scope or out.

That said, one of the topic areas of this site is ebook authoring, which by extension likely includes production.
I would like topics related to the structure of ebooks to be on topic and included in this stackexchange site. They're intrinsic to the books themselves; and the devices, the formats, etc. are all on topic. 

By sharing our understanding of the structures, how to create, modify, and use them, we may help people to publish and repair ebooks.