The majority of the transparencies in PH Series 2427 are arranged by the hierarchically-based numerical code used by the department through the 1970s. A typical code number is 21/3/17/10-6(1), a view of a snowmobile derby at Eagle River. The numerical system roughly grouped images by subject, and thus for the previous example, the more general number 21/3/17/10 seems to refer to recreation with snowmobiles. Unfortunately, the precise meaning of the numerical codes has been lost, and internal evidence suggests that the system was more complex than simple subject arrangement. Individual variants of a single image are not all arranged together by the code system. Furthermore, the system is not exclusive; other pictures including snowmobiles are scattered elsewhere in the series.
During the 1970s the department introduced an alphabetical subject file for its photographs that also included primary and secondary topical subdivisions to define subjects more precisely. Thus a typical description might be “Fisheries-Management-Test seining.” Some, but not all, of the transparencies were assigned to these subject categories, and some images did not receive topical subdivisions. Once again, the subject categories were not consistently applied so variant views of one image might have several different subject classifications.
An index table follows that includes both the numerical codes applied to particular images, as well as any subject headings that were assigned.
