[OSM-dev] Difference between osm and osmChange formats

[Andy Allan]

On Wed, Jun 1, 2011 at 2:34 PM, Frederik Ramm <frederik at remote.org> wrote:

> We have full history OSM files and normal OSM files (both use .osm extension
> and <osm>...</osm>), and we have simple diffs and replication diffs (both
> use .osc and <osmChange>...</osmChange>).
>
> Normal OSM files never have a "visible" attribute, and they contain at most
> one version of every object.

Not quite true - API map calls return normal OSM files with the
visible attribute set.

> Objects in full history OSM files contain a "visible" attribute, and these
> files may contain different versions of the same object, with at most one
> having visible=true.

Again, not quite true - full history files returned by the api history
calls contain different versions of the same object, where many
versions can be shown with the visible=true attribute.

Perhaps it could be summarised as "There are many different pieces of
software generating both normal and full-history OSM files, and simple
and replication diffs, and the visible attribute may or may not appear
in any of them." :-)

Cheers,
Andy