Bliss Bibliographic Classification (BBC) uses a combination of letters and numbers as its notation system. The 21 main classes are represented by a single letter, with the exception of class 10 (Generalities), which is represented by the letter “X”. Each main class is then divided into subclasses using decimal numbers. For example, the subclass 5.1 (Mathematics) would be located in class 5 (Pure Science) and would represent the area of mathematics within the field of pure science.
In addition to the letters and numbers, BBC also uses a system of relative index terms to further specify the subject of a particular work. These index terms are represented by a combination of letters and numbers and are used to provide additional detail about the content of a work.
For example, a work classified using BBC notation might be represented as “QX 5.1 B3”, which would indicate that the work is classified in class 10 (Generalities), subclass 5.1 (Mathematics), and is further specified by the index term “B3” (which represents a specific topic within the field of mathematics).