• Specifying new units
• Built-in conversion factors
• Creating and reading libraries of contaminants and decays

• Base units is the process by which water on the ground surface enters the soil
• Dervied units is the transfer of heat or matter by the flow of a fluid
• Prefixable units are sections of our model where we assume things are well-mixed; there is no spatial variation of anything within the compartment
• Libraries are physically distinct parts of the model (i.e., they have different physical properties). They may be discretised into multiple compartments).

This video covers section 5.5 of the User Guide.