_default_ mapping

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Deprecated in 6.0.0.

See Removal of mapping types

The default mapping, which will be used as the base mapping for a new mapping type, can be customised by adding a mapping type with the name _default_ to an index, either when creating the index or later on with the PUT mapping API.

The documentation for this feature has been removed as it no longer makes sense in 6.x where there can be only a single type per index.