what is the grade attribute ID to use to build a default rule in Advanced Expression

Summary:

Fusion Global HR : What is the grade attribute that can be used in an Adv Expression for Default expression

• Fusion Global HR : What is the grade attribute that can be used in an Adv Expression for Default exp
We need to create a default rule where in we need to default date created in the work relationship DFF field for select grades/grade codes using Advanced expression
However while writing the code --we are unable to achieve this 
Want to know what is the correct grade /grade code attribute we need to use.

We are using this now-->gradeCode = $fields.addPersonWorkRelationships.GradesLov.GradeCode.$value();