Updated 19th March 2015:
England has some 140,000 miles of footpaths and many are a delight to walkers. The various classifications of public rights of way are well described on the website of the Institute of Public Rights of Way and Access Management.
"Definitive Maps" are kept by local authorities in England and Wales (Wildlife and Countryside Act 1981 section 53) and the map is conclusive evidence as to certain matters (section 56). If there is dispute as to whether a route over the ground is a public right of way then the first port of call should be this map. The Act contains a process for modifying the maps and an application has to be accompanied by a map drawn to a scale of not less than 1:25,000 (the "map requirement").
The Trail Riders Fellowship are seeking
to have the status of "Byway open to all traffic" (BOAT) confirmed in relation to 5 ancient lanes in Dorset described in an article in The Guardian 14th January as "tranquil tracts of the
county far inland from busy tourist beaches." Dorset County Council refused to accept the applications because, they argue, the map requirement was not met because the Trail Riders submitted computer-enlargements from a map drawn originally to scale 1:50,000. Whether these enlargements meet the "map requirement" is the subject of an appeal in the Supreme Court of the UK. Certainly, maps drawn originally to 1:25,000 might be expected to reveals more detail than the smaller scale 1:50,000. The Supreme Court (Lords Neuberger, Clarke, Sumption, Carnwath and Toulson) heard the case on 15th January and judgment is awaited.
In May 2013, the Court of Appeal (Civil Division) Maurice Kay, Black and Rafferty LJJ ruled that the enlargements met the map requirement - Judgment here. Supperstone J -  EWHC 2634 (Admin) - had agreed with the Council's interpretation.
Parliament - Establishing Rights of Way
Update 19th March:
By a 3 to 2 majority, the Supreme Court held that the enlarged maps met the requirement of the legislation.
R (on the application of Trail Riders Fellowship and another) (Respondents) v Dorset County Council (Appellant)