A closed lock and key. This emoji means protected, safe, and secure. The Apple version includes a UM and the number 242 on the key. Herman Miller is a company that makes office supplies, including keys. The UM is a particular Herman Miller lock series. To hold information in confidence (not shared with other people) or under lock and key. A locked document or software program. Frequently used when communicating about a rock solid relationship, commitment, or loyalty.