Now that we've gotten to "some of these macros are unused", (and due to your persistence, for which I credit you), I have looked at this enough to agree that there is some vestigial remnant of thinking that may have been apropos at one time but has become, at least for now, inapplicable. > \[W\]ould the comment at the top saying that these defines can be used to override linkage be technically incorrect ...? I would agree that if "these defines" means "each and every one of these defines", then the comment's assertion is incorrect. I'm not so sure (as you) that we should interpret comments in the code with a contract-writing lawyer's precision. I read the comment as "This set of defines is intended to allow so and so." However, being fond of precise locution myself, I would give you the point on this contention. But I must say that I am glad that SQLite's authors have spent their time more on the code than on trying to satisfy lawyerly readers. I am tempted to volunteer to clean this up, to the extent it needs cleanup. That extent is the crux. I'm working on something more useful and likely welcome at the moment. (Well, moments not spent writing posts.) We (SQLite developers) recognize that the docs can better approach perfection, and that some of the code can be improved for clarity and ease of maintenance. Among all such possible improvements, I have to say that this falls close to the bottom in my estimation. I mean no offense by this.