conditional formatting

[Guest]

I have set up a conditional format that will change the color of a cell when
a value changes higher or lower from the previous cell in the column. My
problem is that I am using a lettering system which goes (A+, A, A-, B+, B,
B-, C+, C, C-, D+, D, D-, E+, E, E-), but the spreadsheet sorts these letters
in this fashion (A+, A-, A, B+, B-, B, etc....). Can someone tell me how I
can change the automatic sorting??? Thanks for your time.

 

[Tom Ogilvy]

See possible solution in answer to later posting of this question.