Sections which are to be segmented are classified, using a system of segment-numbers and the following criteria:
Sections which must be available for reference at all times, or which are referred to very frequently, are normally classified as belonging either to one of the overlayable fixed segments or to one of the permanent segments; sections which are used less frequently are normally classified as belonging to one of the independent segments, depending on logic requirements.
Generally, the more frequently a section is referred to, the lower its segment-number; the less frequently it is referred to, the higher its segment-number.
Sections which frequently communicate with one another should be given the same segment-numbers.