On Tue, 8 Aug 2017, Jochen Topf wrote:
I would urge you to keep the order because that makes many things much
more efficient. For instance checking whether a file contains an object
twice is trivial when there is a known order but very expensive without.
My code for assembling multipolygons for instance needs to make sure
that IDs aren't in a file twice and it uses this very efficient way
instead of creating much more complex data structures which would need
more RAM and make everything slower.
In general we will not make any changes only to do changes. So the chance
that element order stays fixed as it is now is high. I'm not aware that it
changed in the past.
BUT: You asked if you can rely on this. And the answer to this is that
this cannot be guaranteed. :-)
But you simply can ignore this and hope that JOSM continues to produce
nice files and chances are high your hope will be fulfilled.
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