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In SI , and other rationalized systems ( for example , Heaviside–Lorentz ) , the unit of current was chosen such that electromagnetic equations concerning charged spheres contain 4π , those concerning coils of current and straight wires contain 2π and those dealing with charged surfaces lack π entirely , which was the most convenient choice for applications in electrical engineering .
 person: Heaviside–Lorentz
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Heaviside–Lorentz 
Answer:
 person: Heaviside–Lorentz