A uniform is a variety of costume worn by members of an organization while participating in that organization's activity. Modern uniforms are most often worn by armed forces and paramilitary organizations such as police, emergency services, security guards, in some workplaces and schools and by inmates in prisons. In some countries, some other officials also wear uniforms in their duties; such is the case of the Commissioned Corps of the United States Public Health Service or the French prefects. For some organizations, such as police, it may be illegal for non members to wear the uniform. From the Latin unus (meaning one), and forma (meaning form). Workers sometimes wear uniforms or corporate clothing of one nature or another. Workers required to wear a uniform may include retail workers, bank and post-office workers, public-security and health-care workers, blue-collar employees, personal trainers in health clubs, instructors in summer camps, lifeguards, janitors, public-transit employees, towing- and truck-drivers, airline employees and holiday operators, and bar, restaurant and hotel employees. The use of uniforms in commercial or public-service organizations often reflects an effort in branding and in developing a standard ; it also has important effects on the employees required to wear uniforms. The term uniform may be misleading because employees are not always fully uniform in appearance and may not always wear attire provided by the organization, while still representing the organization in their attire. Academic work on organizational dress by Rafaeli & Pratt (1993) referred to uniformity (homogeneity) of dress as one dimension, and conspicuousness as a second. Employees all wearing black, for example, may appear conspicuous and thus represent the organization even though their attire is uniform only in the color of their clothing, not in its features. Pratt & Rafaeli, (1997) described struggles between employees and management about organizational dress as struggles about deeper meanings and identities that dress represents.