If you look at the example below, you will notice several lines of code begins with model.component("comp1").mesh("mesh1").

The Use Shortcut button is used to simplify code by replacing these instances with a variable name.

In the example above, the mouse pointer has been positioned at mesh1 at the first occurrence of model.component("comp1").mesh("mesh1"). Click the Use Shortcut button to open the Use Shortcut dialog as shown below.

The code starting with the prefix model.component("comp1").mesh("mesh1") has been replaced with the variable mesh1. This variable is stored as a shortcut in the Declarations node, as shown in the figure below together with the corresponding Settings window.

If you instead position the mouse pointer at comp1, then the first part model.component("comp1") will be replaced with a variable comp1.