Centimeters (cm) - Metric unit of length.
Feet (ft) - Imperial unit of length.
Inches (in) - Imperial unit of length.
Kilometers (km) - Metric unit of length.
Meters (m) - Metric unit of length.
Miles (mi) - Imperial unit of length.
Millimeters (mm) - Metric unit of length.
Points (pt) - Typographic unit of measurement (1/72 of an inch).
Yards (yd) - Imperial unit of length.
Represents one of the units to which you can scale from for measurement annotations.