between stations A and B is used by a certain number of
trains and should therefore comprise one track unit.
Between station B and a switch called C, the line is double
tracked, while it is single tracked between C and D; these
two parts of the line should be registered as separate track
units. Since the traffic load differs, sections D–F, F–G and
F–H should also comprise separate units. Major marshalling
yards, such as E, are accounted for separately as are
some major stations such as D. The Swedish (presented in
Section 2.1) and Finnish (Section 2.2) data sets are
organized along these lines.