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The DESTINATION_ORDER policy controls how each subscriber resolves the final value of a data instance that is written by multiple DataWriter objects (which may be associated with different Publisher objects) running on different nodes.

The setting BY_RECEPTION_TIMESTAMP indicates that, assuming the OWNERSHIP policy allows it, the latest received value for the instance should be the one whose value is kept. This is the default value.

The setting BY_SOURCE_TIMESTAMP indicates that, assuming the OWNERSHIP policy allows it, a timestamp placed at the source should be used. This is the only setting that, in the case of concurrent same-strength DataWriter objects updating the same instance, ensures all subscribers will end up with the same final value for the instance. The mechanism to set the source timestamp is middleware dependent.

The value offered is considered compatible with the value requested if and only if the inequality offered kind >= requested kind evaluates to TRUE. For the purposes of this inequality, the values of DESTINATION_ORDER kind are considered ordered such that BY_RECEPTION_TIMESTAMP < BY_SOURCE_TIMESTAMP.

Source: DDS 1.4 Spec