## Rational

Some uom are a combination of multiple uoms. Defining this combination would allow to calculate a variable depending of the uom categories implied in the combination.

Some examples: Speed = length /time (km/h), Density = weight/volume (Kg/m³) or even existing Tryton uom categories : Surface = length * length , Volume = Surface * length

## Proposal

Defining a new model “cross_uom” that would define uom categories “linked” together. Considering uom_category_1 * uom_category_2 = uom_category_result * coefficient(1 by default).

Each uom_category will use by default the base uom.

Combination of the 3 uom_categories would be unique.

- uom_category_1
- uom_category_2
- operation : * or / or …
- uom_category_result
- coefficient : default 1