[Tagging] Wiki Edit War on using/avoiding semicolon lists

[Peter Wendorff]

Am 22.01.2015 um 21:18 schrieb Martin Koppenhoefer:
> a minor issue with semicolon separated lists: we don't have yet defined how to escape actual semicolons in values.

Hi,

Is that an issue?
IMHO it's only an issue for tags where the values are "names" as a
semicolon can be avoided easily for any enum/set-value defined by the
community.

If we split the discussion by this assumption in two parts, it might be
easier to come to a conclusion:

Case 1) A tag with a set of agreed-on values, like amenity, landuse,
cuisine and much more:

On those tags escaping is not an issue as we can avoid values that
contain semicolons.

Case 2) Names in the broadest sense: ref, addr:*, name...

Here the semicolon might appear in a single value, although it's a
relatively rare case I think. I can imagine semicolons to occur in
housenumbers, where a house is signed with number 3;5 or something like
that.

Here we have to discuss if multiple values are "allowed" or not. In case
of ref current practice seems to be to allow it, for name= it's at least
not handled by much consumer software and circumvented by using other
tags like alt_name, name:[lang] and more.

Perhaps we should define some kind of "tagging patterns" to reflect that
and motivate to define those patterns in the wiki documentation.

Patterns could be:

(1) Single free text value
(2) Enum (one of a predefined set of values)
(2a) Flag (yes/no)
(3) Set (one-or-more of a predefined set of values)
(4) Sequence (e.g. for a "sequence" of lanes from left to right or vice
versa, again one-or-more of a predefined set of values, but here the
order of values is semantically important

Probably there are more of course, like natural numbers or similar

Examples:
(1) name/name:*, addr:street, addr:city and so on
(2) most of the "feature" tags, like amenity, cuisine, landuse
(2a) lit, intermittent, an Bushaltestellen shelter und bench...,
vending:*=,
(3) common "fallback" for mappers who don't decide for one, and a common
alternative to the flags-pattern (2a) like at vending=
(4) colours on seamarks [1], in principle lanes, although there | (the
pipe) is used for the sequences and the semicolon for sets.

regards
Peter



[1] http://wiki.openstreetmap.org/wiki/OpenSeaMap/Colours