I don't think so. Where do we need null values in OSM?
As you said, maxspeed=none means something like maxspeed=unlimited.
I can't think of any tag key which should be stored in OSM with a null value.
In what case would that add valud information compared to having no such tag ?
Gerd
________________________________
Von: Colin Smale <colin.sm...@xs4all.nl>
Gesendet: Sonntag, 24. Januar 2016 10:58
An: Tag discussion, strategy and related tools; Tijmen Stam
Betreff: Re: [Tagging] Removing name_1 and alt_name_1 from Wiki
At present the string "none" is actually a value, the interpretation of which
is specific to the key "maxspeed" . Maybe we should promote it to the
equivalent of NULL in SQL.
On 24 January 2016 10:43:16 CET, Tijmen Stam <mailingli...@iivq.net> wrote:
With the value "none"
For example on German Autobahnen, where you can drive as fast as you
want is "maxspeed=none" which is different from having maxspeed not set:
this means maxspeed is unknown or not tagged yet.
On 20-01-16 09:06, Colin Smale wrote:
Exactly.
If a missing value (i.e. use the default) is not the same as explicitly
having NO value, how do you override the default with "no value"?
--colin
On 2016-01-20 08:50, Gerd Petermann wrote:
I don't think that the meaning really depends on the position. My
understanding is that the
complete value (e.g. "80||" ) is parsed by splitting it into separate
strings at each pipe symbol.
Result: three strings: "80" , "",""
The value "|80|" also gives three strings: "","80",""
Another point is that an empty value means "use the default", which can
only make sense in special cases like this.
Gerd
________________________________
*Von:* Colin Smale <colin.sm...@xs4all.nl>
*Gesendet:* Mittwoch, 20. Januar 2016 08:23
*An:* Tag discussion, strategy and related tools
*Betreff:* Re: [Tagging] Removing name_1 and alt_name_1 from Wiki
I meant that there is a value missing "between the pipes", which at a
slightly higher semantic level can mean "use the default". A
definition which varies according to position doesn't feel well-formed
to me.
//colin
On 2016-01-20 08:10, Gerd Petermann wrote:
Colin Smale wrote
The "lanes" tag family uses a different delimiter ("|"), sometimes
together with a semicolon to make a kind of 2-d array. A
double pipe
("||") indicates a missing value there. Wouldn't it be nice if
we were
consistent?
That is new to me. My understanding of a double pipe is that
described here:
http://wiki.openstreetmap.org/wiki/Proposed_features/lanes_General_Extension#Default_values
Proposed
features/lanes General Extension - OpenStreetMap
Wiki<http://wiki.openstreetmap.org/wiki/Proposed_features/lanes_General_Extension#Default_values>
wiki.openstreetmap.org
A
simple, straightforward extension of existing tags to specify properties not
only for a way as whole but for the lanes of the way instead. Based on this
general ...
Proposed features/lanes General Extension - OpenStreetMap Wiki
<http://wiki.openstreetmap.org/wiki/Proposed_features/lanes_General_Extension#Default_values>
wiki.openstreetmap.org<http://wiki.openstreetmap.org>
A simple, straightforward extension of existing tags to specify
properties not only for a way as whole but for the lanes of the
way instead. Based on this general ...
which indicates that a double pipe means one or two default values,
depending on the position.
At the end of the value, it means two default values.
Gerd
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