Variables can be used as attribute values for circuit components. This allows
you to update common attribute values for the whole circuit in one go. To add
a new variable, right click on the Variable item in the navigation
window. This will allow you to define a new variable. To edit, rename or remove
an existing variable, right click on the variable name.
You can also define range variables, which are used for tuning the circuit. To define a variable as a range variable, the value of the variable must be in the format "min value":"current value":"max value", for example:
10:50:100
This will define the variable with a minimum value of 10, a current value of 50, and a maximum value of 100.