Possible, but a pretty big hassle to setup. You'll need 5 "Release" transitions, all with the same name and permissions, but conditions on each. This will look like one transition from the user standpoint but will use the conditions to pick which one to use. One will work if REV A, 0, 1, 2 are blank and writes to REV A. Another will see if REV A isn't blank and 0, 1 and 2 are and write to 0. The same for A, 0 not blank and 1, 2 is blank; then A, 0, 1 not and 2 blank. The 5th will check to see if they're all filled then implement the shifting process from that article. Good luck!