Override Rule

Add an Override Rule node (), to define new override rules in addition to the exclusive and contributing types.

When creating a model in the Model Builder, you add several feature instances as children to a physics interface. If these features support selections, they obey certain rules about how a feature of one type overrides or gets overridden by another feature. This is not to be confused with features being applicable to a certain entity, for example some features only apply on interior boundaries.

The overriding of selections is based on grouping features into override types, and the rules apply between override types. The four standard built-in override types are. Exclusive, Contributing, Override features of same type, and Never overridden. In addition to the built-in override types you can create custom override types. The names and behavior of override types are defined in an Override Rule node.

To add an Override Rule node:

•	On the Home toolbar, click Override Rule (), or

•	Right-click the Auxiliary Definitions node () and select it from the context menu.

You can access all added rules from any feature in the same file, or in any other file that has the former file added as an Import node under the External Resources branch.

Override Rule

The table that displays all override types as a matrix with the types as rows, and what types they override as columns. A selected cell means that the row type overrides the column type. The predefined rules are exclusive, which overrides other exclusive or contributing nodes, and contributing, which does not override other exclusive or contributing nodes. You can add and define new override types by clicking the Add () button. The override rule table defines the override behavior of the included override types. There are two things to keep in mind when editing these tables:

•	Firstly, the defined override rules need to obey the following rule: If type A overrides type B and type B overrides type C, then type A must also override type C.

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Secondly, an override table does only define the override behavior of the types included in the table. A physics interface can use override types defined in different tables for its features. In this situation the override behavior between some features might not be well defined. To remedy this, you can provide the missing information in an override table that is available in the Physics Interface node’s Override Rule section. This table contains all the override types used by the features under the physics interface.

The Settings window also allows for setting a name for the override rule. This is done by changing the Identifier setting from Default to Customized and then typing a name in the Name field that is made visible. The reason for setting the name is that the override rule may then be used in an Override Rule Filter node.

Physics Exclusive and Contributing Node Types in the COMSOL Multiphysics Reference Manual