rank is applied consistently throughout the organisation and that it is applied only based on an individual's role. A number of ranks will cease to exist as a result of this change, and the requirements for many of the remaining ranks will change. In December 2016, it was announced that effective 1 January 2017, no rank is to be worn on events, except by persons who are performing an operational management role at that event. Persons who are undertaking an operational management role, but who do not have rank, will continue to not wear rank. Persons who do have rank, but who are not in an operational management role at the event should not display their rank. National variations Whilst this article uses English St John Ambulance practice as standard, inevitably national variations in rank structure have occurred as the organisation has spread to other countries, and subsequently developed in those countries with a degree of autonomy. The English types are presented in the illustrative tables below. Ranks in other countries are usually similar, but adopt local terminology such as (for example) "Provincial Commissioner" instead of "County Commissioner". There may also be fewer ranks in smaller countries, as a result of the need for fewer rungs of management structure. Unique Rank Slide Specifications In 2013, St John Ambulance UK rolled out a new design of rank slide. While the insignia, colours and text font remain unchanged, the slides themselves are now much longer and wider, with insignia being much larger. This updated design for rank slides corresponds with the rise of the Service Delivery Uniform (SDU), rolled out in 2011. This is the first modification to the design of the rank slides since the change from cloth and thread to rubber-made rank slides with a new font for 'St John Ambulance' title on all slides. This was later abandoned. Role-Based Variations In a similar fashion to the Police, St John Ambulance used to have a number of role-based variations on the standard rank markings detailed below. For large-scale events where a Gold, Silver, Bronze command structure is used, the Silver and Bronze commanders used to wear white and orange rank slides respectively. This is no longer the case. The organisation has a number of specially trained Medical Response Team volunteers who operate in dense crowds. The teams operate in units of 3 with a designated Supervisor, Clinical Lead and an