Uphill vs. incline=up - direction of travel

I have need for tagging that a restriction on a road is only valid in case a vehicle is driving uphill.

The traffic sign states “Snow chains required when ice or snow on road, except for AWD cars driving uphill[1]. This is indicated on both sides of the road section, both driving uphill and downhill.

That would call for a conditional specification of a direction or condition with the aspect of direction in relation to elevation.

The first idea was to use incline=up like
snow_chains=required @ (ice; snow)
snow_chains:motorcar:conditional=default @ (awd AND incline=up)

It was pointed out that ‘incline’ is a tag and intended to indicate a direction and amount of inclination of the road in relation to the mapping direction, not the direction of the vehicle driving on the road.

’uphill’ was proposed, to be adopted from mtb:scale:uphill

There is however a accepted specification for relative direction longitudial-wise in relation to the way: Forward, backward, left, right (also see Proposal) [^note1]).
These are defined to be used as key suffix or value.

The improvement seems to be to instead use ‘uphill’ either
as direction as key suffix
snow_chains=required @ (ice; snow)
snow_chains:motorcar:uphill:conditional=default @ awd

or as condition
snow_chains=required @ (ice; snow)
snow_chains:motorcar:conditional=default @ (awd AND uphill)

The direction key suffix approach seems to integrate better, but mappers could mistake it and use it instead of :forward and :backward, making it impossible to interpret without inlination information. Using it in the condition seems to split direction information from other direction information.

[^note1]: I could not find an accepted proposal for that, bit was implicated in the the proposal for conditional restrictions that it was accepted at that time of the :left and :right proposal in 2009 Proposed features/right left - OpenStreetMap Wiki?

I will add the other supporting reasons why I raised this: (main reason being it is the exact condition signposted)

  1. This is easier to add to a long length of road, without having to check their direction; and reverse some of them while fixing any other suffix, or add snow_chains:motorcar:backward:conditional= instead of snow_chains:motorcar:conditional= for those in the other direction.
  2. It will not be as easily broken by other edits if some are reversed accidentally, or unsuspectingly without fixing. In case this is too complicated, and for other reasons not handled by software automatically changing the suffix. Or a user didn’t check the JOSM prompt, or was doing other editing process that missed this.