Section 69.401 - Direct expenses(a) Plant Specific Operations Expenses in Accounts 6110 and 6120 shall be apportioned among the interexchange category, the billing and collection category and appropriate access elements on the following basis:(1) Account 6110-Apportion on the basis of other investment apportioned pursuant to § 69.309 .(2) Account 6120-Apportion on the basis of General and Support Facilities investment pursuant to § 69.307 .(b) Plant Specific Operations Expenses in Accounts 6210, 6220, and 6230, shall be apportioned among the interexchange category and access elements on the basis of the apportionment of the investment in Accounts 2210, 2220, and 2230, respectively; provided that any expenses associated with DS1/voice-grade multiplexers, to the extent that they are not associated with an analog tandem switch, assigned to the local transport category by this paragraph shall be reallocated to the local switching category; provided further that any expenses associated with common channel signalling included in Account 6210 shall be assigned to the local transport category.(c) Plant Specific Operations Expenses in Accounts 6310 and 6410 shall be assigned to the appropriate investment category and shall be apportioned among the interexchange category and access elements in the same proportions as the total associated investment.(d) Plant Non Specific Operations Expenses in Accounts 6510 and 6530 shall be apportioned among the interchange category, the billing and collection category, and access elements in the same proportions as the combined investment in COE, IOT, and C&WF apportioned to each element and category.(e) Plant Non Specific Operations Expenses in Account 6540 shall be assigned to the interexchange category.(f) Plant Non Specific Operations Expenses in Account 6560 shall be apportioned among the interexchange category, the billing and collection category, and access elements in the same proportion as the associated investment.(g) Amortization of embedded customer premises wiring investment shall be deemed to be associated with § 69.303(b) IOT investment for purposes of the apportionment described in paragraph (c) of this section.52 FR 37313, Oct. 6, 1987, as amended at 62 FR 31939, June 11, 1997