[Tagging] Best practices regarding implied tags

[Matthew Woehlke]

On 16/09/2020 18.32, Paul Johnson wrote:
> No, it's not wrong to add implied tags explicitly.  It's actually
> encouraged in some cases where the implicit tag is not consumable by
> automated system (such as the "none" default for turn:lanes tends to be
> ambiguous between "you can't turn from this lane" and "you can't use this
> lane" and "there's an implicit but unspecified implication that isn't
> painted on the ground")

Pedantic: wouldn't "you can't turn from this lane" be correctly 
specified as turn:lanes=through? As I understand turn:lanes, "none" 
would be "you can't use this lane". (Also pedantically speaking, a blank 
value would mean there are no specific markings. I think the only 
ambiguity here is that it's unclear if the tag is simply missing — in 
which case the truth on the ground could be *anything* — or if there are 
no markings. Sort of like how a missing oneway could mean oneway=no, or 
could mean oneway but not tagged.)

(Incidentally, I tend to add oneway=no whenever possible... or at least 
I did in iD, which made it easy. I can't recall now how well I've been 
keeping that up with JOSM.)

-- 
Matthew