41 CFR 302-7.3: -7.3 Shipping professional books, papers, and equipment (PBP&E).

(a) The agency may pay for shipping PBP&E as a discretionary item. When authorized, shipping PBP&E is considered an administrative cost to the agency. However, for ease of administration in calculating this allowance, PBP&E should be included as part of the HHG shipment, if possible. That is, if the net weight of the HHG plus the PBP&E is less than 18,000 pounds, the agency should ship the items together and pay for the HHG shipment in one payment.

(b) Any PBP&E that was transported as an administrative expense of the Government to the OCONUS assignment will be returned as an administrative expense of the Government to the place of actual residence or any other location, not to exceed the cost to the authorized destination.