The Metaparameter Explorer allows you to calibrate a variable using an expression.
To open the Metaparameter Explorer, right click on the required function and choose Add Usage.
For example, if you want to calibrate a link variable, you can specify this in the Metaparameter Explorer, and then assign it a value using the Function manager.
Suppose you want to calibrate the storage routing exponent (m) on one of the reaches in a Source model. Initially, idenitfy which link in the model you want to place the expression in. Then, use the Metaparameter Explorer to allocate a parameter to the variable (steps outlined in Figure 1).
Figure 1. Metaparameter Explorer