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This compresses all versioned edits made to the version to which you are connected only.
If you did not complete step 1 before unregistering but did check Compress all edits in the Default version to the base table, you will lose any edits made to versions other than the version to which you were connected. If you did not complete step 1 before unregistering and did not check Compress all edits in the Default version to the base table, you will lose all edits in all versions.