Let us suppose that a user of this site receives an answer to a question of his or hers, but (s)he cannot understand some passages in the proof and, after asking the answerer for clarifications, either the answerer refuses to explain the passages or does not answer after a reasonably long time - say two weeks, for example - has passed.
What is appropriated in such a case to do in order to ask for clarifications? Let us notice that clarifications could benefit not only the asker, but also other people reading the site and having the same difficulties, or even lead to the correction of errors that might well exist in a human made proof.
Would it be allowed to post a separate question containing only the passages that have not been understood? If it would, how should one word a question asking for such clarifications?
Moreover, does an official Stack Exchange policy exists or can the rules change from a site to another?
I apologise if this question already existed, but, after searching some keywords, I cannot find an answer to this issue.