In the published accuracy statement of an electronic total station, the value 0.2 mm in ±(0.2 mm + 5 ppm) refers to which type of constant?

• A. Factory
• B. User
• C. Distance-dependent
• D. Prism

Answer: (C)

In total-station accuracy statements, the distance measurement error is modeled as a fixed offset plus a term that grows with distance: error ≈ fixed_offset + (coefficient × distance). The 5 ppm part is the distance-dependent component, since it scales with how far you measure. The 0.2 mm is the fixed offset that accompanies that distance-proportional term. When you’re asked what type of constant the 0.2 mm represents within that model, it’s described in the context of the distance-dependent error expression, i.e., it’s part of the distance-dependent accuracy formulation. The other options describe separate, specific constants (factory-calibrated, user-set, or prism-related) and don’t fit the role of being part of the distance-dependent error model.