Changes to letter grade capture

Is there space within the Ed-Fi data standard that provides a space for adding in the description of a Grade Mark? The question arises as some districts use grade marks other than the traditional A, B, C, D, F. Grade Marks such as EE - Exceeding Expectations.
Another example is where the traditional Grade Marks are given a description by State Legislature. Example - see the attached document pages 2-3, lines 19-45

AC: 

• Quick pros and cons of the move
• suggested data model for the change
• proposed descriptor values
• look If there are existing elements that could apply
• look at deprecation options