20:10:28:03Assignment of book costs -- General.

In assigning book costs to categories, the costs used for certain plant classes are average unit costs which equate to all book costs of a particular account or subaccount; for other plant classes, the costs used are those which either directly approximate book cost levels or which are equated to match total book costs at a given location.

Source: 19 SDR 111, effective January 31, 1993.