[OHM] Representing the Change in Tag Values over Time

[Richard Welty]

On 4/3/17 6:48 PM, Tommy Bruce wrote:
> What About a key with 3 modifiers?  
> We would have to completely redo the tagging schemes, but what if it
> was Highway=Tertiary=(Start date)=(End date)
> As for how to display features that have a double tag, I think it
> would be relatively easy to figure out.  
i wouldn't use the = sign as a separator more than once. using
additional characters
(such : ; ,) on the right side of the equal sign can be ok, but may
require software work
to support. there is precedence for it, e.g.

ref=US 9; US 20

for highways with two route designation.

keep in mind that we probably want to use some kind of ISO derived date
format so we
would want to avoid parsing ambiguities by avoiding special characters
that might appear
legitimately in a date.

also keep in mind that in the OSM database schema, you can only have one
tag with a specific
name per entity (node/way/relation). so highway can't appear more than
once per entity for
example.

richard

-- 
rwelty at averillpark.net
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