information:filtering, linguistic:voice_change, linguistic:paraphrasing, linguistic:translation, structural:reformatting
Heraldry

Keys appear in various symbols and coats of arms, the best-known being that of the Holy See: derived from the phrase in Matthew 16:19 which promises Saint Peter, in Roman Catholic tradition the first pope, the Keys of Heaven. But this is by no means the only case. Many examples are given on Commons.