Document ignoreDelete

advanced/folder-ignoredelete.rst

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+ignoreDelete
+============
+
+``ignoreDelete`` is an advanced folder setting that affects the handling of
+incoming index updates. When set, incoming updates with the delete flag set
+are ignored.
+
+Example Scenario
+----------------
+
+Assume two devices, "Alice" and "Bob", sharing a folder. Bob has set
+``ignoreDelete``.
+
+New and updated files are synchronized as usual between Alice and Bob. When
+Bob deletes a file, it is deleted for Alice as well. When Alice deletes a
+file, Bob ignores that update and does not delete the file.
+
+In this state, Bob is fully up to date from his own point of view, as is Alice
+from her own point of view. However from the point of view of Bob, who ignored
+the delete entry from Alice, Alice is now out of date because she is missing
+the file that was deleted.
+
+Should Bob modify any of the files that Alice has deleted, the update will be
+sent to Alice and Alice will download the now updated file.
+
+.. note::
+	 Ignoring deletes in both directions between two devices can be a
+	 confusing configuration.