Break Material Attributes
The Break Material Attributes expression is ideal when using a Layered Material - a feature of the Material Functions system. When using a Material Layer Function within a Material, you may want to use only one aspect of the layer. For example, you may have a Material Layer that defines a nice looking generic Material, such as steel. You may want to use only the Roughness and Base Color attributes from that layer in your final Material, rather than using the whole thing. In such cases, you can use a Break Material Attributes node to split up all of the incoming attributes of the Material Layer, and then just plug in the ones you want. This also allows for complex blending of various Material Attributes.