Right-click an External Material List node to add a
Socket Output subnode (

) where you can defined an output for the external material.
Define the Variable name field for the name of the variable that the external material will send its output to.
From the Socket output quantities list, choose the physical quantity of the socket output.
From the Type list is typically preset and unavailable.
In the Expression field, enter an expression for the output quantity that defines the value to send from the external material.
The options in the Selection list and
Output entities list define the selection where this variable definition is valid. See
Specifying Selections for more information.
See Preferences for the Variable Definitions node.
Set preferences that enable protection of entered expressions. Select the Hide expression in equation view check box to remove the definition to display in the
Equation View node, which is a subnode to a physics feature in the Model Builder. This disables any possibility to alter the expression; it also makes it harder to read the expression.
To further complicate reading of the expression, you can select the Encrypt expression check box. This turns on an encryption of the expression in the saved model file and when accessing the expression in a model file for Java code. It also encrypts the tensor expression when you compile the archive (see
Compiling an Archive), so the expression in a distributed builder file (
*.mphphb) cannot be read.