[Tagging] Multi-value tagging and Lane Groups

[Colin Smale]

On 08/02/2012 13:40, Martin Koppenhoefer wrote:
> 6. building:levelPlan=*	What each storey is used for, Examples: 0-2:
> shop, 3-12: residential; 0: restaurant, 1: residential; -1: unused, 0:
> lobby, 1: restuarant, 2-12: offices, 13: unused, 14-66: offices
> ->  missleading key (one would expect a link to a level plan IMHO). Why
> should we suggest a key that is crying for multivalues? We don't use
> capital letters in key names (see beginners guide, 1.4.1). This could
> become:
> building:level:0:use=restaurant building:level:1:use=residential
Another area crying out for this multi-value approach is the "lane 
group" business, which has been going round in circles for a long time.

     lane:1:access=no
     lane:1:psv=yes
There you go - an instant bus lane.

     lane:3:minoccupants=2
Gives you a carpool lane.

     lane:3:maxwidth=2
Lane with width restriction

     lane:2-3:intended_direction=turn_right
     lane:2-3:destination=London
     lane:2-3:dest_ref=A2
Two lanes for turning right on the A2 towards London - information only, 
not affecting routing. Side-effect: lays the foundations for improved 
routing instructions.

Existing tags can easily be reused, now applying at the individual lane 
level, possibly explicitly overriding tags at the way level. Just needs 
agreement on a system for numbering the lanes (outside-to-inside sounds 
OK, starting at one for the normal lanes, then lane zero can be the hard 
shoulder).

I have not got involved with the recent discussions about lane groups 
because as far as I can see they are all overly complex to understand 
and implement. A standardised approach to array-valued tags is the way 
to go IMHO. If we are prepared to discuss changing the basic tag syntax, 
we could think of "lane[2]:psv=yes" but that would have a lot more impact.

Colin