In Ecolego it is not necessary to specify units for each object. This entry is optional. However, the user should specify the unit of the simulation time step and materials (if materials are included in the model) before starting a simulation. The default unit for the simulation time step is Year but can be changed in the simulation settings window.

Units are specified in the properties page when editing blocks. Some objects like compartments and transfers cannot be assigned units because they are implicit from the materials and time unit of the model. For instance, if the unit for the material “Arsenic” is set to “kg” and the simulation time unit is set to “year”, the unit of a compartment will be (kg) and the unit of a transfer will be (kg/year).

Use ^ to enter exponents, for example: m^2 s^-1 will be displayed as (m² s^-1)

To specify unit notations such as “freshweight” or “particle” you can use a ”.”. For example: kg.fw will be displayed as (kg_fw).

The unit suffix is important for unit checking, see below.

There is no automatic unit conversion in Ecolego.

By default Ecolego will not perform unit checking. To enable this feature, open the errors and warnings page of the preferences screen.

The unit checking algorithm is strict - there might be cases (for instance with empirical relationships) where the unit checker will report an error even if there is none. Also, when using suffixes, the unit checking algorithm will refuse to accept mixing of quantities. For instance, the expression rho(kg/m³) = m (kg_part)/V(m³) will fail because kg != kg_part.

The default unit for radionuclides is Bq. The unit must be the same for all radionuclides, so when the unit is changed from Bq to mol for one radionuclide the unit of all other radionuclides will change.

Bq; s; year^-1; min; h; d; week; month; year; mol.

• Expression syntax