Cal. Gov't Code § 8594.11
(b)
(4) Upon activation of an Endangered Missing Advisory, the Department of the California Highway Patrol may use a changeable message sign if both of the following conditions are met:
(c) A law enforcement agency may request an Endangered Missing Advisory be activated if that agency determines that all of the following conditions are met regarding the investigation of the missing person:
(d) For purposes of this section, the following definitions apply: