Wikipedia
D-book
The D-Book is the UK technical specification for Digital terrestrial television (DTT).
The Digital TV Group (DTG) has published and maintained the D-Book for over a decade and the specification is updated annually to keep up with the pace of development in UK DTT. The D-Book is compiled by DTG Working Groups composed of industry experts from the DTG’s staff and membership of around 150 broadcasters, manufacturers, technology providers and other organisations who continually update and peer-review the specification. Conformance to D-Book standard allows products to use the Digital Tick, Freeview, Freeview + and Freeview HDlogos.
The D-Book is only available to members of the Digital TV Group.