At present, FileMaker Pro lets me auto-enter the "[User] Name" or the "Account Name" in a Text field whenever a record is modified. (The "User Name" can be set under "Preferences", but nobody wants to have to do that every time they switch computers, and way too often people wouldn't remember to do it anyway, so it's practically worthless for these purposes.)
But neither "[User] Name" nor "Account Name" is what I want to have auto-entered in my "Updater Name" field. I want to auto-enter the "LogIn Name" (a Global Text field) that my users are required to specify whenever they open the file. No problem with my "Creator Name" field (just auto-enter a calculated result from "LogIn Name") nor my "Obsoleter Name" field (handled with a script). But how does the record know it's been modified so I can populate my "Updater Name" field only when the record has actually been changed (and specifically not upon original record creation)?