I worry we're veering very much off topic, so let me state, for the benefit of anyone thinking that this is still about the original comment, that I consider the quote provided by abnercoimbre to be both correct and relevant to the submitted topic. The rest of this comment is not about that.
No, I do not consider a document to be a part of another document, unless it's embedded in the other document. I don't, for example, consider the RFC 2822 [1] to be a part of the RFC 5322 [2] event though they are obviously related and the latter refers (and, indeed, links) to the former. If, in a conversation about the 5322, someone quoted the 2822 without providing a reference to it, I would find it confusing.
As for "Choose Your Own Adventure" books, I'll have to admit that I don't have much experience with them, but from what I believe I know about them, I'd say that I would not consider the whole book to be a single document when it comes to referencing. Would it make sense to say something like "The adventure in the book ends with you caught by the security guard" if that is just one of the many alternative endings, one that many might not encounter when playing?
And expanding on that, would you consider it appropriate referencing to say "That is a crime according to the French criminal law" without specifying where it says that? (I'm assuming here that the French criminal law is a single document.)
The other example is interesting. I would consider a wrong (or broken) link to be an error in the document, but I would not consider erroneous statements in the linked document to be inaccuracies or errors in the linking document. Imagine that instead of an outdated policy, the linked document was one promoting homeopathy. Would you say that the original document contains misleading statements about healthcare? I would not.
[1] https://www.rfc-editor.org/rfc/rfc2822
[2] https://www.rfc-editor.org/rfc/rfc5322