Figure 22-5 shows how the Nodes (and by implication, the Paths and Networks linking them) are placed on the Earth. From Chapter 5, the figure shows Geographic Point, a singular point in three dimensional space. Each Node is identified as being at exactly one Geographic Point.

Describing the Geographic Point can be done various ways, depending on the Reference System involved.

This could be the “Geographic Coordinate System” (latitude and longitude), a “Cartesian System” (X, Y, and Z coordinates), or the “Linear Reference System” (LRS)—a system where features (points or segments) are localized by a measure along a linear element.[79]. Other Reference Systems could also be used.

Each Reference System is defined in ...

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