A new instance of a source/sink of a particular type is created by selecting the Add button for the type. This creates a new source/sink and displays a default value or set of values for the source/sink in the edit fields on the right side of the dialog. If the simulation is steady state, normal edit fields are used to enter the values. If the simulation is transient, buttons appear which can be used to bring up the XY Series Editor. A value is entered for each of the defined stress periods. Multiple instances of a source/sink can be created by repeatedly selecting the Add button. Each cell can contain multiple sources/sinks of a particular type or a mixture of several types.