Of changesets and updating
The same user can have multiple active changesets at the same time.
A changeset has a maximum capacity (currently 10,000 edits), maximum lifetime (currently 24 hours) and idle timeout (currently 1 hour).
Changesets were introduced with API v0.6 in April 2009.
Changesets were "synthesised" for edits before that date.
You are then free to use this result to add additional errors to the changeset via the method, if applicable.
For example, if you are using an Ember Data model in your route, saving the changeset will save the model.
Each changeset has zero, one or two parent changesets.
It has two parent changesets, if the commit was a merge.
A changeset consists of a group of changes made by a single user over a short period of time (see also: editing).
It has no parent, if the changeset is a root in the repository.
There may be multiple roots in a repository (normally, there is only one), each representing the start of a branch.
One changeset may for example include the additions of new elements to OSM, the addition of new tags to existing elements, changes to tag values of elements, deletion of tags and also deletion of elements.
Edits can only be added to a changeset as long as it is still open; a changeset can either be closed explicitly (see your editor's documentation), or it closes itself if no edits are added to it for a period of inactivity (currently one hour).