Curvature correction is subtractive because the Earth's curvature causes the line of sight to be above the horizontal at long distances, requiring a subtraction to obtain true elevations.

Wrought iron is the purest commercially available form of iron with very low carbon content and minimal impurities; it is malleable and tough compared to cast iron which contains higher carbon making it brittle and steel variants which are alloys with controlled carbon contents.

Lime also called calcium oxide forms the major proportion in Portland cement and combines with silica and alumina during burning to form the key strength giving compounds of the cement. Adequate lime content ensures development of early and long term strength while too little or too much can respectively cause low strength or unsoundness. Although silica clay and alumina are important constituents lime remains the principal ingredient by percentage.

Remote sensing systems can be passive, relying on external illumination like sunlight, or active, emitting their own energy such as radar, so both categories apply.

A stretcher is a brick laid with its longer face parallel to the wall. It is the most common arrangement in stretcher bond and is distinct from headers which are laid with their shorter end towards the face.

In residential and public buildings, the minimum height of a door is typically between 1.8 to 2.0 meters to allow convenient access for people.

Cast steel is chosen for high grade instruments due to its fine grain structure, ability to be hardened and tempered, and precision in machining. It offers better quality than mild or Bessemer steel.

A no parking sign imposes a legal restriction on driver behavior by prohibiting stopping or parking at a location and therefore belongs to the class of regulatory signs which indicate rules and regulations that road users must obey. Warning and informatory signs provide cautions or guidance but do not enforce compliance in the same way as regulatory signs.

An invar tape made from a nickel-iron alloy has minimal thermal expansion and is used for precise measurements in surveying where temperature stability is important.

Metamorphic rocks form under heat and pressure from pre existing rocks. Slate and quartzite are metamorphic while shale is sedimentary. Therefore the correct answer includes slate and quartzite.