OpenStreetMap
There's no widespread use yet. Wiki has no clear suggestion. I distilled
highway=path
snowshoe=yes
_or_
highway=path
snowshoe=designated
access=no
{for exclusivity osm.wiki/Tag:access%3Ddesignated}
and optional:
relation=route
route=snowshoe
name=....
Discussion
Reäksje fan Kevin Steinhardt op 26 desimber 2009 om 15.23 oere
Just one question: what's a snowshoe? :P
Reäksje fan bass op 26 desimber 2009 om 21.21 oere
http://www.usscouts.org/clipart/library/WOSM/Canada/General/snowshoe.gif
Reäksje fan Skippern op 26 desimber 2009 om 22.06 oere
snowshoe=designated (when wearing snowshoes you are obligatory to use this route even if alternatives exists)
snowshoes=yes (you are allowed to use this with snowshoes)
snowshoes=no (you are not allowed to use this with snowshoes)
The only sane usage I can see with this is together with ski-tracks, where I would understand usage of snowshoes might damage the prepared tracks, and therefor prohibited or regulated in some way. If it is a regular "snowshoe walking route" or "snowshoing event" than relation=route should be used.
Reäksje fan Iridium op 4 jannewaris 2010 om 07.51 oere
Of course, I thought of routes that only exist when there is snow that are only doable with snowshoes. Well you could do on foot, but would sink like knee deep into snow... otherwise a simple "snowshoe=yes" on whatever would be enough.