# Knob

The Knob is useful principally for providing initial values for Stocks. Knobs also can be used to adjust values for constants. Unlike the Slider, the Knob cannot be adjusted during the course of a simulation. It is set prior to the outset of a simulation and remains fixed throughout the simulation. Variables which contain equations or graphical functions can not be assigned to a Knob.

Knobs work well for selecting one of multiple scenarios available to the model user. The model user may "dial up" a scenario number at the start of the simulation. You may only assign one variable per Knob.