41 C.F.R. § 102-39.20
The following definitions apply to this part:
Acquire means to procure or otherwise obtain personal property, including by lease (sometimes known as rent).
Combat material means arms, ammunition, and implements of war listed in the U.S. munitions list ( 22 CFR part 121 ).
Excess property means any personal property under the control of any Federal agency that is no longer required for that agency's needs or responsibilities, as determined by the agency head or designee.
Exchange means to replace personal property by trade or trade-in with the supplier of the replacement property.
Exchange/sale means to exchange or sell non-excess, non-surplus personal property and apply the exchange allowance or proceeds of sale in whole or in part payment for the acquisition of similar property.
Executive agency means any executive department or independent establishment in the executive branch of the Government, including any wholly owned Government corporation.
Federal agency means any executive agency or any establishment in the legislative or judicial branch of the Government (except the Senate, the House of Representatives, and the Architect of the Capitol and any activities under his/her direction).
Historic item means property having added value for display purposes because its historical significance is greater than its fair market value for continued use. Items that are commonly available and remain in use for their intended purpose, such as military aircraft still in use by active or reserve units, are not historic items.
Replacement means the process of acquiring personal property to be used in place of personal property that is still needed but:
Service Life Extension Program (SLEP) means the modification of a personal property item undertaken to extend the life of the item beyond that which was previously planned. SLEPs extend capital asset life by retrofit, major modification, remanufacturing, betterment, or enhancement.
Similar means the acquired item(s) and replaced item(s):
Note 1 to the definition of "similar": Only one of the criteria in this definition needs to be met for the property to be considered "similar" for an exchange/sale transaction.
Surplus property means excess personal property not required for the needs of any Federal agency, as determined by GSA under part 102-37 of this chapter.
41 C.F.R. §102-39.20