i had a quick look at the wayfinder maps. the navit wiki article regarding via-michelin maps applies to some extent. maps consist of a number of qt files, each holding a feature layer. you can lookup the filenames as shortcodes on the teleatlas site or in the .reg files. eg: pc.qt is postcodes. each fil has a header plus a number of zlib compressed blocks. i successfully decompressed a pc block and could see the pc but have not looked any further.