I've been trying to find how to mark duplicate product codes. The excel file is for recording document changes. Each row contains the data relavent to the change. One column represents the documents affected by the change. The documents all have differen't naming standards and are listed in the cell like this "XHD89d, 88-0345b, NO45.KDg". The last letter represents the revision of the document. I'm wanting excel to flag cells if one of the document codes is the same as in another cell within the column. Ie one cell contains "45-9930j, FF55.JKb" and another "45-9930j, 33-0989h" so the cells would be highlighted indicating that another person has associated that document revision with their change. This is to avoid two people working on the same document at once. Once the change has been approved the document revision is updated so the next person wouldn't input the same value, ie 45-9930j -> 45-9930k. I've found some things about looking at each cell but not if the cell contains some comma separted list. Any ideas?