Custom attributes are like custom parameters added by the user. Custom attributes are reference targets, and can be assigned to other parameters in the scene. Custom attributes behave like IParamBlock2 parameters in several ways:

• They are saved and loaded in the scene file along with the object.
• They can be animated and keyframed.
• They are displayed in Track View along with the base parameters.

A custom attribute is represented by an instance of the class CustAttrib. A collection of custom attributes are represented by an instance of the ICustAttribContainer class.

For an example of custom attributes see the how-to sample at maxsdk\howto\utilities\customattribute.