In Publication 207, Wisconsin presents information regarding the classification of certain products and services typically provided by contractors. Among other things, the publication clarifies that computer cabling is a part of communications equipment, retaining walls are real property regardless of whether or not they are decorative, and underground piping at a service station qualifies as tangible personal property. Additional information in the publication clarifies details of the exemption that applies to materials used to construct real property for a Native American Tribe on its reservation. (Publication 207, Wisconsin Department of Revenue, September 7, 2004)