[OSM-talk] [tagging] RFC open - new key - towpath=yes

[Gervase Markham]

Most canals have towpaths. One could just have a way alongside which is 
otherwise unassociated, but it seems to make sense to indicate the 
towpath's status as such, so it can be unambiguously picked out for 
rendering on e.g. canal maps. This is particularly important where the 
towpath leaves the canal (e.g. for tunnels).

http://wiki.openstreetmap.org/index.php/Proposed_features/Towpath

Gerv