To avoid alarming their visitors, hospitals typically alert their staff to emergency situations by announcing “codes” over the public address system. Alberta uses these:

Code Red: Fire
Code Blue: Cardiac arrest/medical emergency
Code Orange: Mass casualty incident
Code Green: Evacuation
Code Yellow: Missing patient
Code Black: Bomb threat/suspicious package
Code White: Violence/aggression
Code Brown: Chemical spill/hazardous material
Code Grey: Shelter in place/air exclusion
Code Purple: Hostage situation

These haven’t been standardized; a few other systems are listed here. One common variation is “Paging Dr. Red” or “Paging Dr. Firestone” to alert staff of a fire. Sometimes “Code Clear” is announced when the emergency has been dealt with.

For similar reasons, airlines refer to dead bodies as “Jim Wilson.” American Airlines’ help desk for funeral homes is called the American Airlines Jim Wilson Service.