Sections represent terrain elevations that cut across surfaces, including corridor surfaces, pipe networks, and grading, which are associated with a specified sample line group. Sections are "sampled" from a source (a surface or corridor shape). In the .NET API the sources for sections are exposed by the SectionSource object. A SampleLineGroup contains a collection of SectionSources, which can be accessed by the SampleLineGroup.GetSectionSources() method.