What table to I join to grade rate to get Grade to prepare for GradeRate.dat HDL load?

Summary

What table to I join to grade rate to get Grade to prepare for GradeRate.dat HDL load?

Content

I am preparing a data model and have all info EXCEPT grade to update grade rates via HDL.  I hope I am just missing something obvious, however....

Below is my from and where clause.  I need to get GradeCode and can't see where to join the grade table to get that value.  I am assuming there is a table that can join back to Per_Grades_F

From
       HRC_INTEGRATION_KEY_MAP Mapp
        ,Per_rate_values_f rval
        ,per_rates_f rraf