There are two police organisations. The social police - known simply as Police to all - wear the traditional uniform and helmet. They are also human and their main duty is to protect the public. They deal with the general public and tourists, and consist of Constables, Sergeants and Inspectors. They are not armed. They may be assisted by Blue Droids. General street patrols, answering calls for help and managing everyday problems are among their duties. The other crime officers are called 'Polis' by androids and robots, and consist of humans, androids and robots. All serious crimes are referred to them. The Polis may be armed, if this is considered necessary. The humans and androids wear a military style of uniform and have military ranks, though the ordinary Polis officer is usually referred to as 'constable'. The uniform colours distinguish the officers function - red, for example, identifies officers of the Ministry for Mechanicals (covering robots and androids). Blue indicates that the wearer is a regular Polis constable of any rank. Green jackets identify employees of the Department of the Environment. Badges of rank are usually worn on the collar.