INTERPOL's colour-coded notices run from the Red Notice for arrest to the Black Notice for unidentified bodies
Background
INTERPOL Notices are international requests for cooperation or alerts allowing police in member countries to share critical crime-related information. They are issued by the General Secretariat at the request of a member country's INTERPOL National Central Bureau and are made available for all member countries to consult in the Notices database. A Red Notice seeks the location and arrest of persons wanted for prosecution or to serve a sentence. A Yellow Notice helps locate missing persons; a Blue Notice collects additional information about a person's identity, location or activities; a Black Notice seeks information on unidentified bodies. A Green Notice warns about a person's criminal activities where the person is considered a possible threat to public safety, an Orange Notice warns of a serious and imminent threat to public safety, and a Purple Notice seeks or provides information on modus operandi, objects, devices and concealment methods used by criminals. A Silver Notice, in pilot phase, is to identify and trace criminal assets. A Notice is published only if it complies with INTERPOL's Constitution and the Rules on the Processing of Data, and it will not be published if it violates Article 3, which forbids the Organization from undertaking any intervention or activities of a political, military, religious or racial character. Most Notices are for police use only, but all United Nations Special Notices are public. Member countries may also circulate a diffusion directly to other countries, following the same colour-coded system.
In plain words
National Central Bureau NCB — The designated police office in each INTERPOL member country that links it to the General Secretariat.
Diffusion — A request a member country circulates directly to other countries instead of through a notice.