20:10:29:28General support facilities -- Apportionment of

investment. General support facilities investment is apportioned among the interexchange, information, billing and collection, and special access categories and common line, local switching, and transport elements based on central office equipment, information origination/termination equipment, and cable and wire facilities, excluding category 1.3, combined.

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