"Reposition Output" used to allow you to tell the the machine to go back and restart or "Reposition Output" from certain page within a currently running job. Lets say you were printing a long run of a variable job and noticed and IQ defect. The idea would be that you could pause the machine/job, fix the issue and then restart it from a previous page to reprint the bad output. I got it to work once on an iGen3 (yes, it's been around that long). Been a long time since I have used it however. Would not suprise me if it did not work. No one really knew what it did so nobody complains that it doesn't worked.
Xerox works of the old service paradigm that if the phone doesn't ring, then nothings wrong. Squeaky wheel gets the grease kind of reaction to customer issues.