A parameter definition determines the structure and metadata of a parameter for a specific project. The definition states the

• Name - Name of the parameter, for instance rho_dry. See naming conventions.
• Full name - Full name of the parameter, for instance Dry density.
• Symbol - Symbol for the parameter, for instance ρ_dry.
• Dependencies - The dependencies of the parameter. The parameter may have a maximum of two dependencies.
• Type - The type of the parameter - either Parameter or Time-series.
• Category - The category of the parameter.
• Description - A description of the parameter.

The definition is used to describe the data of a parameter instance.

• Database design
• Parameter instance
• Parameter entry
• Parameter value