I don't think I knew about 700MHz either, but these things are a moving target.
Ofcom confirmed the 700Mhz clearance last November towards the end of 2015's World Radiocommunication Conference, having previously announced the clearance a year before that with a latest target date of 2021.
Part of the reason given by DTG for some of the d-book 8 changes for tuning was to ensure that new equipment could easily handle major frequency reorganisations, including the 700Mhz clearance.
http://www.digitaluk.co.uk/about_digital_uk/digital_uk_blog/D-Book_gets_smart_to_improve_retuning
Moving target indeed. I'm not sure what the long term plan is for people who have C/D group aerials if they do stop broadcasting freeview at 700mhz as the range for these aerials is 690mhz and up?
Among the preparation activities there are some negations to be done with the owners of COM7 and COM8 licensees which will effect the plans and the dates. The aim is to start updating some transmitters Autumn 2017, so hopefully there will be a change map by then. The current target for completion is 2020. Who would have financial assistance should their aerial require changing and how that would be handled has not been revealed yet, and appears to be still under discussion judging my one of the questions in the consultation that ended in May.
I think I read on A516's website that Arqiva are trying to negotiate some retention of COM7 and COM8 until 2023 as part of the early removal of COM7 & COM8 from their current slots to enable the reshuffle of the frequencies for the other multiplexes for 700Mhz band clearance, and so the outcome will be interesting.
My expectation is that where the PSB multiplexes are within the original group for a transmitter then there will be an attempt not to change those to a frequency that is out of group.
For those whose PSB multiplexes are currently in the 7000Mh band, A516digital has an example from Ofcom of how much Winter Hill
could have its frequencies changed.
http://www.a516digital.com/2016/04/ofcom-seeks-input-on-freeview-changes.html. Also included in that link is what appears to be an extract from one of the Ofcom document of which main transmitters are expected to have the most shakeup, possibly
http://stakeholders.ofcom.org.uk/bi...arance-cfi/summary/700_MHz_Implementation.pdf or
https://cai.org.uk/downloadables/fi...try-and-consumers-ready-for-700-mhz-clearance
edit 7/7/16: Corrected sentence beginning 'I think'.