[Feature Request]Make a distinction between JOSM formats and standard OSM formats. (对JOSM特有格式和普通OSM文件做出区分)

[LaoshuBaby]

For example, in 3380702

This commit imported a action attribute, and only used in JOSM to emphasis the changes and diff.

Or you can see <bound>, this also only mentioned in JOSM's format, used for describe downloaded area and ensure this can be reloaded after JOSM restarted.

See: https://wiki.openstreetmap.org/wiki/JOSM_file_format

Should this part of support be put on hold? We should base on API 0.6 instead of adapting to JOSM (although this is a must consider support)

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例如，在3380702 中引入的这个action，是仅JOSM用来区分diff才会有的格式。

再比如，<bound>也是JOSM中引入的概念，比如已下载区域之类，保证存档重开以后还能知道哪些区域没被下载过。

可见https://wiki.openstreetmap.org/wiki/JOSM_file_format

这部分支持是否应暂缓？我们应以API 0.6为基础，而非适应JOSM（虽然这是一个必须考虑的支持）

[LaoshuBaby]

查看发现level0和CGImap亦开始采用，这个issue关掉吧