These documents were originally published by the Radio Authority, one of the organisations replaced by Ofcom at the end of 2003. It represents Ofcom's current policy. The following information comprises details of the technical parameters of all analogue VHF, MF, and DAB transmitters (including services on multiplexes) currently on-air. In-use parameters are included mainly for listeners and aerial installers who may wish to know more about the nature of the signals they are receiving and possibly optimise their aerial accordingly. The maximum allowed parameters (within the terms of each licence) for analogue services are also included for the benefit of those, principally in the industry, who wish to make calculations, particularly about interference, for coverage-planning purposes. The format is intended more for ease of download and transfer into specialist databases, than for presentation.