I have a column of ID's that go by the format of 'rs#####', but occasionally I get 'rsundefined' if that ID is missing. In order to do the analyses I desire every ID must be unique, which means that it reads all of the ID's 'rsundefined' as duplicate entries. Thus, I need sort of a find and replace script, except everything it find the word undefined I would like it to add on a different integer to the end of it (ie rsundefined1, rsundefined2, etc etc) so that every ID is unique. Thanks for any help.