Interoperability
================

.. Release Notes from this point.

:critical:`[Critical]` messageLength field was required in RTPS HEADER_EXTENSION for checksum calculations
----------------------------------------------------------------------------------------------------------
Previously, |me| required that the ``messageLength`` field be
present in the RTPS HEADER_EXTENSION if a checksum was also included in
the HEADER_EXTENSION. If the ``messageLength`` was not present, it was
considered an error and the RTPS message was discarded.

Now, the ``messageLength`` field is optional. If it is not included, the
``messageLength`` will be assumed to be the size of the message payload.

|me| and |core_pro| always include the
``messageLength`` in the HEADER_EXTENSION when a checksum is being sent.
This fix will resolve compatibility when using checksums with other DDS
implementations.


[RTI Issue ID MICRO-7172]