The UCS, for "Universal Category System", is a public domain initiative by Tim Nielsen, Justin Drury and Kai Paquin, among others. This is a list of fixed and consistent categories for classifying sound effects. It provides consistency in a filename structure to make naming and categorizing easier for anyone who maintains their own personal or professional library. This sound library meets the UCS 8.1 categorization.
To find out more, visit the UCS website