the star rating, the more comprehensive a product. The scores for each product are totaled and all products ranked. Industry experts determine the scores necessary to achieve 1, 2, 3, 4 and 5 star ratings. Military ranks The most senior military ranks in all services are classified by a star system in many countries, ranging from one-star rank which typically corresponds to brigadier, brigadier general, Commodore or air commodore, to the most senior five-star ranks, which include Admiral of the Fleet, Grand Admiral, Field Marshal, General of the Army and Marshal of the Air Force—some five-star ranks only exist during large-scale conflicts. Other American college football Recruits entering American college football are commonly ranked on a five-star scale, with five representing what scouts think will be the best college players. Transport safety International organisations use a star rating to rank the safety of transportation. EuroRAP have developed a Road Protection Score which is a scale for Star Rating roads for how well they protect the user from death or disabling injury when a crash occurs. The assessment evaluates the safety that is 'built into' the road through its design, in combination with the way traffic is managed on it. The RPS protocol has also been adapted and used by AusRAP, usRAP and iRAP. Euro NCAP awards 'star ratings' based on the performance of vehicles in crash tests, including front, side and pole impacts, and impacts with pedestrians. The United States National Highway Traffic Safety Administration (NHTSA) also uses a star ranking to rank the safety of vehicles in crash tests, including front, side, pole impacts, and rollovers, with 5 stars being the most secure. Voting and preferences Some web content voting systems use five-star grades. This allows users to distinguish content more precisely than with binary "like buttons". Many recommender systems, such as MovieLens or Amazon.com, ask people to express preferences using star ratings, then predict what other items those people are likely to enjoy. Predictions are often expressed in terms of the number of predicted stars. Unicode The Unicode Standard encodes several characters used for star ratings in the Miscellaneous Symbols and Arrows block: The STAR WITH LEFT HALF BLACK and LEFT HALF BLACK STAR are intended for use in left-to-right contexts where the half star is positioned to the right of one or more whole stars, whereas the STAR WITH RIGHT HALF BLACK and RIGHT HALF BLACK STAR