Check cell for valid data

[excelbobabc]

When the user enters data into a cell, I need to verify the data.
The valid data options are EL MR MW. If the user enters one of these I don't want to do anything. If the user enters an incorrect value I want to change the cell to 'error' I am currently doing this in VBA but would like to do it in a worksheet function if possible.

Thanks,
Bob Hiller

[jasoncw]

Why not just use data validation to prevent an incorrect input altogether?

Data > Validation, on the Settings tab, allow List, then in the list, include:

EL,MR,MW

You can enter a pop-up message when incorrect data is entered on the Error Alert tab.

HTH

Jason