It is said of the libraries of Elysium that "[they] can't even have 'be quiet' signs up, [...] people would ignore them out of spite".

There are no such signs up in Heaven's libraries; the locals would be quite attentive to any signs, but they're not necessary at all. Decorum is observed on decorous frequencies, and doesn't have to be observed on others, and no one is interrupted in their studies save by priority interrupts they would, in fact, rather hear than not, which are vanishingly rare here in peaceful Requius. (Visiting mortals are requested to have an archon escort, however.)