[gdal-dev] osm_id vs osm_way_id?

[Djordje Spasic]

Hello,
I am converting an .osm file to shapefile, and there is one thing that I do not understand:

What is the difference between: osm_id and osm_way_id fields (keys)?

They are defined in osmconf.ini file, but only for [multipolygons].
Here is an explanation from the osmconf.ini file:

# note: for multipolygons, osm_id=yes instanciates a osm_id field for the id of relations
# and a osm_way_id field for the id of closed ways. Both fields are exclusively set.
Does that mean that osm_way_id will be used to represent the osm id number of a closed way, while osm_id will only be used for to represent the osm id number of relations?

It's a bit confusing concept.

What makes the closed ways so special so that they need to have their own special field (osm_way_id)?
Why wasn't there a separate field for relations instead: like: osm_relation_id, while closed ways would use the osm_id.

Thank you for the reply.
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