A Plot Menu Definition node (

) defines the plot menus that you can group related variables into (see
Variable Declaration).
A plot menu shows up as a submenu in the Replace Expression (

) menu of the result nodes in the Model Builder. Specify another menu name as parent if you need several levels of submenus; otherwise leave the parent field blank.
The plot menu that a variable belongs to is specified under the variable declaration node below the Show in plot menu option. Using plot menu definitions you can create a structure where related variables are grouped into separate menus.
The Settings window has the following section:
In the table under each column, enter the Name,
Description, and
Parent to define a new menu. Select the check box in the
Show Add all column to add the
All expressions in this group option to that group of plot variables.