Unlike any other published scheme, the STB classification collocates pure sciences with their technologies. The rationale behind this arrangement was that any reader interested in technology would find relevant material in books on the pure science, and that the reader's time would be saved by minimising the amount of walking round the book stacks demanded of him. Main classes within the scheme are defined on the basis of traditional academic disciplines or fields of study. This means that there will be more than one place within the scheme for a given topic. For example tin has aspects which fall under several disciplines such as chemistry, metallurgy, and geology.
Classification is always by discipline or aspect studied, then by topic within the discipline.
Within each main class topics are arranged hierarchically. This means that every topic is subordinate to and part of all the broader topics above it. Topics are included in the schedules on the basis of literary warrant rather than an abstract division of knowledge. The starting point is always a close analysis of the actual literature of the subject. The STB classification scheme is enumerative not synthetic in structure.