What code is used to notify that a subject is in custody?

The correct code used to notify that a subject is in custody is "Prisoner." This term is specifically utilized in law enforcement and legal contexts to denote an individual who has been taken into custody by law enforcement officers. It effectively communicates the status of the individual, indicating that they are no longer free and are in the legal care of authorities, typically due to an arrest.

The term "Arrest," while related, refers to the action of taking someone into custody rather than the status of the individual afterward. "Incarceration" relates to being confined in a jail or prison after an arrest but does not specifically denote the immediate status of someone who has just been taken into custody. Similarly, "Custody" is a broader term that can encompass various types of custody arrangements and does not specifically signify the status of an individual as formally recognized within the law enforcement framework as the term "Prisoner" does.