Units defines the units of measurement available across the system and the physical quantity each one belongs to, so weights, lengths, areas and other values stay consistent and comparable wherever they're used.

Each unit has a symbol, a physical quantity such as length, area, or weight, a display format, and a usage that sets whether it can be used as a component unit, a product unit, or both. Grouping units by physical quantity is what keeps values comparable within the same dimension and scopes the unit pickers elsewhere in the system to the right kind of measurement.

Click Add unit and start typing the unit's name in the Search or add unit field. If the unit already exists it appears for you to select; if it isn't there, choose to create a new one, then enter its name and symbol, set whether it can be used for component units and product units, and save.

Mass add opens a single text box for entering several units in one go. You type each unit as its name, symbol, and physical quantity followed by a flag for component use and a flag for product use — an x means yes and an empty value means no — and you separate one unit from the next with a semicolon. Clicking Import units creates them all together.