Exchanges involving personal property afford clients the ability to engage in the most diverse types of exchanges possible. Generally, the taxable gain on the disposition of most personal property assets is primarily due to the depreciation taken over the life of the asset and is less likely to be due to the combination of depreciation and appreciation in the asset’s value, such as is common in the sale of real property assets. To qualify for exchange treatment, personal property assets must be either “like-kind” or “like class”. Tangible depreciable personal property is considered "like class" if it falls within the same General Asset Class, or Product Class as described in Sectors 31 through 33 of the North American Industry Classification System (NAICS). For example, a backhoe is not like-kind to a bulldozer, but a backhoe and a bulldozer are like class because they are both identified with the same NAICS code for construction machinery and equipment. Exchanges involving tangible depreciable or non-depreciable personal property assets include such assets as industrial machinery, aircraft, passenger vehicles, trucks, collectibles, artwork, construction and agricultural equipment, racehorses and livestock, marine vessels and electric generation equipment. To add to the large variety of personal property exchanges, clients can exchange “like-kind” intangible personal property assets, such as broadcast spectrums, franchise licenses, wireless telephone licenses, and copyrights of books, music and software.