The principle of division used in the EBACS classification system, which is in force in all of the European market economies, is the type of business activities actually conducted by business entities.

The European Business Activity Classification System (EBACS) has five levels with one additional indirect level for some sections.

The first level (section) divides the population into categories of types of business activities, grouping actions associated with one another from the traditional point of view, concerning the overall division of labour. These categories are labelled with a one letter alphabetic code.

The indirect level (sub-section) appears only in these sections which include industrial activities, viz. in Section C: "Mining and Querying" (2 sub-sections) and in Section D: "Manufacturing" (14 sub-sections). This level is labelled with a two-letter alphabetic code.

The second level (division) divides the general population into categories of types of business activities, grouping actions by those features which are of substantial significance in specifying the degree of similarity, as well as in considering the links in the national economy (e.g. in the tables of inter-industrial flows). This level is labelled with a two-digit numerical code.

The third level (group) includes those categories of business activities which may be separated, concerning the manufacturing process employed, the designation of the output, the nature of the service or the consumers of these services. This level is labelled with a three-digit numerical code.

The fourth level (class) includes those categories of business activities which may be separated, concerning the manufacturing process or service provision specialisation. This level is labelled with a four-digit numerical code.

The fifth level (sub-class) was introduced in order to single out those types of business activities that are typical in the Polish economy and which are the subjects of statistical observation. This level is labelled with a six-digit numerical code.