By case number. Early case files are prefixed by “U” and “2U,” for all types of utility cases. In 1975, the PSC adopted a file number system which used a combination of utility file numbers and case file numbers. For example, “6700-WR-1” designates a water rate case (“WR”) for the Wisconsin Rapids Waterworks and Light Commission (utility file number “6700”). Codes under this sytem include: “DT” (depreciation telephone), “DW” (depreciation water), “EI” (environmental impact), “ER” (electric rate), “GR” (gas rate), “TR” (telephone rate), “UI” (utility investigation), “UR” (utility rate), and “WR” (water rate).
