now reverted to regular rank titles (with the prefix "special"), only some have reverted to regular rank insignia. Senior special constables have no authority over regular officers, but very experienced officers may occasionally be given administrative supervision of mixed units of regular and special constables for certain events where no regular supervisory officer is available. Trainee, temporary and acting ranks Constables who are training to become detective constables sometimes bear the title trainee investigator (T/I) or trainee detective constable (T/DC). The prefix "temporary" before a rank (e.g. temporary detective sergeant, abbreviated T/DS) denotes an officer who has been temporarily promoted to a rank (and so who does actually hold that rank, albeit on a temporary basis), whilst the prefix "acting" (e.g. acting inspector, abbreviated A/Insp) denotes an officer who is performing the role of a higher rank than the one actually held (sometimes informally termed "acting up"). Temporary ranks are often used for set periods (e.g. a six-month appointment to a particular role), whereas acting ranks, although sometimes held for extended periods, are often used for a very short time (e.g. a single shift when additional supervisory officers are required, or to replace an officer on short-term leave). Under section 107 of the Police and Criminal Evidence Act 1984 (England and Wales only), sergeants and chief inspectors may be designated (by an officer of at least the rank of superintendent) to exercise the powers of an inspector or a superintendent respectively. Such a designation will generally accompany such an officer being given an acting rank, so for most operational purposes there is no difference between substantive, temporary and acting ranks at Inspector and above (although there may be differences as to pay, pensions and insignia). However, under section 36 of that act, only substantive sergeants may be appointed custody officers. Ranks of unwarranted related services Police cadets Ranks within volunteer police cadet schemes vary considerably across the territorial police forces. Police community support officers (PCSO) Police community support officers, in general, do not have a rank system. The South Yorkshire Police and Kent Police, however, have designated PCSO supervisors. Traffic wardens Traffic wardens were administered by the police and exercised some police powers to control traffic or issue fixed penalty notices for traffic offences. Very few police Traffic Wardens now exist with a legacy of only 10 police traffic wardens remaining in England & Wales. Section 46 of the Policing