UNI Re-parenting requrements

The following just dropped onto my world, listed under planned engineering works
on my line (which is on the Portsmouth North exchange)

PEWNumber PW051113: Break in Service of between 10 and 20 minutes.This work is
needed to ensure that future UNI re-parenting requirements can be accomplished
using a proven process

Anywone got a clue as to what 'UNI Re-Parenting requirements' are?